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Honors Chemistry2016-2017

WS 8.1 Stoichiometry: Mole to Mole Conversions1. The reaction that takes place in an alkaline flashlight battery as the battery is

discharged is: Zn + MnO2 + H2O Zn(OH)2 + MnO(OH)

Remember to balance the equation.

a. How many moles of Zn react when 0.200 moles of MnO(OH) is formed? (0.100)

b. How many moles of H2O react with 0.150 mol of Zn? (0.300)

c. how many moles of Zn(OH)2 are formed when 0.100 moles MnO2 reacts? (0.050)

d. How many mole of H2O react when 0.600 moles of MnO2 reacts? (0.600)

2. Hydrazine, N2H4, and hydrogen, H2O2, have been used as rocket propellants. They react according to the equation:

H2O2 + N2H4 N2 + H2O

a. How many moles of N2 are formed from 0.0250 moles of N2H4? (0.0250)

b. How many moles of H2O2 are required if 1.35 moles of H2O is to be produced? (0.675)

c. How many moles of H2O are formed if 1.87 moles of N2 is produced? (7.48)

3. During the naval battles of the South Pacific in World War II, the U.S. Navy produced smoke screens by spraying titanium tetrachloride into the moist air where it reacted according to the equation:

TiCl4 + H2O TiO2 + HCl

a. How many moles of H2O are needed to react with 6.50 moles of TiCl4? (13.0)

b. How many moles of HCl are formed when 8.44 moles of TiCl4 reacts? (33.8)


4. How many moles of sodium will react with water to produce 4.0 moles of hydrogen in the following reaction? (8.0)

Na + H2O _ NaOH + H2

5. How many moles of lithium chloride will be formed by the reaction of chlorine with 0.046 moles of lithium bromide in the following reaction? (0.046)

LiBr + Cl2 LiCl + Br2

6. Aluminum will react with sulfuric acid in the following reaction: Al + H2SO4 Al2(SO4)3 +_ H2

How many moles of H2SO4 will react with 18 moles of Aluminum? (27)

7. In the above reaction, how many moles of each product will be produced? (9.0; 27)

8. Propane burns in excess oxygen according to the following reaction. C3H8 + O2 CO2 + H2O

How many moles of carbon dioxide are formed from 3.85 moles of propane? (11.6)

9. Using the equation from #8, if 0.647 moles of oxygen is used in the burning of propane, how many moles each of CO2 and H2O are produced? How many moles of C3H8 are consumed? (0.388; 0.518; 0.130)

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WS 8.2 Stoichiometry involving grams1. Consider the reaction :

4 Na(s) + O2 (g) 2 Na2O (s)

a. How many moles of sodium are required to produce 120 grams of sodium oxide? (3.9)

b. How many moles of oxygen gas are required react with 145.5 grams of sodium? (1.582)

c. How many moles of sodium oxide are produced if 75.3 grams of oxygen gas are used? (4.71)

2. In the reaction:AlCl3 (aq) + 4 NaOH (aq) NaAlO2 (aq) + 3 NaCl (aq) + 2 H2O (l)

a. How many moles of sodium hydroxide will react with 125 grams of aluminum chloride?(3.75)

b. How many moles of water are produced when 56 grams of sodium hydroxide react with excess aluminum chloride? (0.70)

c. How many moles of sodium hydroxide are needed to produce 500 grams of sodium chloride? (11.4)

3. Glucose is used as a source of energy by the human body. The overall reaction in the body is

C6H12O6 + O2 CO2 + H2O

a. Calculate the number of moles of oxygen needed to oxidize 12.5 grams of glucose?(0.417)


4. Ammonia is synthesized from hydrogen and nitrogen according to the following equation. N2 + H2 NH3

a. If an excess of nitrogen is reacted with 3.41 grams of hydrogen, how many moles of ammonia can be produced? (1.14)

5. If 120.0 grams of sodium carbonate reacts with calcium hydroxide, how many grams of sodium hydroxide are formed? (90.6)

Na2CO3 + Ca(OH)2 2 NaOH + CaCO3

6. When 80.0 grams of calcium chloride react with silver nitrate, how many grams of silver chloride are produced? (207)

CaCl2 + 2 AgNO3 Ca(NO3)2 + 2 AgCl

7. If 90.0 grams of barium chloride reacts with sulfuric acid, how many grams of barium sulfate are produced? (101)

BaCl2 + H2SO4 BaSO4 + 2 HCl

8. If 500 grams of potassium iodide reacts with lead acetate, what mass of lead iodide is formed? (700)

Pb(C2H3O2)2 + 2 KI PbI2 + 2 KC2H3O2

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WS 8.3 More Stoichiometry Problems Involving Grams

1. In a single displacement reaction, 9.23 grams of aluminum react with excess hydrochloric acid. How many moles of hydrogen will be produced? (0.513)

2. Calculate the mass of silver bromide produced from 22.5 grams of silver nitrate in the following reaction: (24.9)

AgNO3 + MgBr2 AgBr + Mg(NO3)2

3. What mass of acetylene, C2H2, will be produced from the reaction of 90.0 grams of calcium carbide, CaC2, with water in the following reaction? (36.5)

CaC2 + H2O C2H2 + Ca(OH)2

4. Chlorine gas can be produced in the laboratory by adding concentrated hydrochloric acid to manganese (IV) oxide in the following reaction. Calculate the mass of MnO2 needed to produce 23 grams of Cl2 (28)

MnO2 +_ HCl MnCl2 + H2O + Cl2

5. How many grams of oxygen are produced by heating 400 grams of potassium chlorate? (156.6)

2 KClO3 2 KCl + 3 O2

6. How many grams of sodium hydroxide will react with 150 grams of phosphoric acid? (183.7)H3PO4 + 3 NaOH 3 HOH +

Na3PO4

7. How many grams of calcium carbonate are required in the preparation of 50.0 grams of calcium oxide?(89.2)

CaCO3 CaO + CO2

8. If 600 grams of calcium hydroxide are neutralized with nitric acid, how many grams of nitric acid are needed? (1022)

Ca(OH)2 + 2HNO3 Ca(NO3)2 + 2H2O


9. How many grams of potassium chlorate are needed in the preparation of 70.0 grams of oxygen? (179)

2KClO3 2KCl + 3O2

10. When 50.0 grams of magnesium react with silver nitrate in solution, how many grams of silver are prepared? (444)

Mg + 2AgNO3 Mg(NO3)2 + 2Ag

11. If 75.0 grams of copper react with mercuric nitrate (in solution), how many grams of mercury can be displaced? (237)

Cu + Hg(NO3)2 Cu(NO3)2 + Hg

12. When 60.0 grams of aluminum react with hydrochloric acid, how many grams of aluminum chloride are prepared? (297)

Al + HCl _ AlCl3 + H2

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WS 8.4 More Stoichiometry Problems (some without equations)

1. If 150 grams of mercuric oxide are decomposed, what mass of oxygen is formed? (11.1) HgO Hg + O2

2. Calculate the mass of in grams of carbon needed to produce 80 grams of carbon dioxide by burning. (21.8)

C + O2 CO2

3. Calculate the mass of sulfur which will react with 40 grams of copper. (10.1) Cu + S Cu2S

4. Calculate the mass of oxygen released by the action of water on 10.0 grams of sodium peroxide. (2.05)

Na2O2 + HOH NaOH + _O2

5. Calculate the mass of silver formed by heating 10 grams of silver oxide. (9.3) Ag2O Ag + O2

6. If 50.0 grams of oxygen react with magnesium, what mass of MgO is formed? (125.9)

7. When 70 grams of zinc react with dilute sulfuric acid, what mass of hydrogen is formed? (2.14)

8. How much aluminum must be oxidized to form 85 grams of aluminum oxide? (45)

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9. How many grams of magnesium chloride are formed when 30.0 grams of magnesium react with hydrochloric acid? (117.7)

10. When 90 grams of sodium hydroxide are neutralized with sulfuric acid, what mass of sodium sulfate is formed? (159.9)

11. Sixty-five grams of calcium hydroxide are formed when calcium oxide reacts with water. How muchCaO is required to prepare this quantity? (49.2)

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Ws 8.5 Limiting Reactants

1. Calcium hydroxide, used to neutralize acid spills, reacts with hydrochloric acid according to the following equation:

Ca(OH)2 + HCl CaCl2 + H2OIf you have spilled 6.3 moles of HCl and put 2.8 moles of calcium hydroxide on it, which substance is thelimiting reactant?

2. Aluminum oxidizes according to the following equation: Al + O2 Al2O3

Powdered aluminum (0.048 moles) is placed into a container containing 0.030 moles of oxygen. What isthe limiting reactant?

3. Chlorine can replace bromine in bromide compounds forming a chloride compound and elemental bromine. Write a equation showing the displacement of potassium bromide with chlorine gas. Then solve the following: when 0.855 grams of chlorine gas and 3.205 grams of potassium bromide are mixed in solution, which is the limiting reactant? How many grams of bromine are formed? (1.92)

4. A process by which zirconium metal can be produced from the mineral zirconium (IV) orthosilicate, ZrSiO4, starts by reacting it with chlorine gas to form zirconium (IV) chloride.

ZrSiO4 +_ Cl2 ZrCl4 + SiO2 + O2What mass of ZrCl4 can be produced if 862 grams of ZrSiO4 and 950.0 grams of Cl2 are available? (You must first determine the limiting reactant). (1096.7)


5. Heating zinc sulfide in the presence of oxygen yields the following: ZnS + O2 ZnO +_ SO2

If 1.72 grams of ZnS is heated in the presence of 3.04 grams of O2, which reactant will be used up?

6. Use the following equation for the oxidation of aluminum in the following problems. Al + O2 Al2O3

a. How much aluminum oxide will be produced if 32 grams of aluminum and 26 grams of oxygen are available? (55g)

b. How many moles of aluminum oxide are formed from the reaction of 0.00638 moles of O2

and 0.00915 moles of aluminum? (0.00425 mol)

c. If 3.17 grams of aluminum and 2.55 grams of oxygen gas are available, which reactant is limiting?

7. In the production of copper from ore containing copper (II) sulfide, the ore is first roasted to change it to the oxide according to the following equation:

CuS + O2 CuO + SO2

a. If 100 grams of copper sulfide and 56 grams of oxygen gas are available, which reactant is limiting?

b. What mass of copper oxide can be formed from the reaction of 18.7 grams of copper sulfide and 12.0 grams of oxygen gas? (15.6)

8. A reaction such as the one shown here is often used to demonstrate a single replacement reaction:

CuSO4 + Fe Cu + Fe2(SO4)3

If you place 0.092 moles of iron filings in a solution containing 0.0158 moles of copper sulfate, what is the limiting reactant? How many moles of iron sulfate will form? (0.0053)


WS 8.6 Stoichiometry Review

1. Consider the reaction: Mg + HCl MgCl2 + H2a. How many moles of hydrogen gas can be produced if 5.5 moles of hydrochloric acid is provided(assuming an excess of magnesium)? (2.8)

b. If 20.0 grams of magnesium reacts with hydrochloric acid, how many grams of magnesium chloride are produced? (78.4)

c. If 2.5 moles of hydrochloric acid is provided, how many grams of hydrogen gas can be produced? (2.5)

d. How much magnesium must be present to produce 100 grams of magnesium chloride? (25.5)

2. Consider the reaction: _ NaI + Cl2 NaCl + I2a. How many grams of chlorine gas must be reacted with sodium iodide if 10.0 grams of sodiumchloride are needed? (6.07)

b. What is the limiting reactant if 150 grams of sodium iodide is combined with 2 moles of chlorine gas?

c. Using the information from #2b, calculate what mass of sodium chloride can be produced. (58.5)

3. Write a balanced equation for the combustion of methane (CH4)

a. If 3.7 moles of CH4 are combined with 8 moles of oxygen gas, how many moles of carbon dioxide are produced? (3.7)

b. How many moles of water are produced if 2.5 moles of carbon dioxide are produced? (5.0)

c. Calculate the mass of water produced if 125.0 grams of oxygen are consumed. (70.31)


4. Consider the equation: Li + CuCl2 LiCl + Cu

a. Calculate the moles of lithium chloride produced when 3.5 moles of copper chloride is used. (7.0)

b. If 150.0 grams of lithium is reacted with 2.0 moles of copper chloride, what mass of lithium chloride can be produced? (169.6)

c. What mass of copper is produced from 18 grams of lithium and 375 grams of copper chloride? (83)

d. How many moles of copper chloride are needed if 25.0 grams of lithium are used? (1.81)

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WS 8.7 Energy and Stoichiometry – Thermochemical Equations

1. Calculate H for a process in which a 5.8 gram sample of methane is burned at constant pressure. (H = –890 kj/mole methane) (-322.6 kJ)

2. The equation for the fermentation of glucose to alcohol and carbon dioxide is: C6H12O6 2C2H5OH + 2CO2

The enthalpy change for the reaction is –67 kJ. Is the reaction endothermic or exothermic? Isenergy, in the form of heat, absorbed or released as the reaction occurs?

3. For the reaction S (s) + O2 (g) SO2 (g) H = -296 kj/mole

a. How much heat is released when 275 grams of sulfur is burned in excess oxygen? (-2535.8 kJ)

b. How much heat is released when 25 mol of sulfur is burned in excess oxygen? (-7400 kJ)

c. How much heat is released when 150.0 grams of sulfur dioxide is produced? (-692.7 kJ)

4. Calculate the enthalpy change when 1.00 grams of methane is burned in excess oxygen according to the reaction: (-55.7 kJ)

CH4 (g) + 2O2 (g) CO2 (g) + 2H2O (l) H = -891 kJ/mole methane

5. Calculate the energy change when 15 grams of carbon dioxide is produced from the reaction: C(s) + O2 (g) CO2 (g) H = -393.51 kJ/mole (-134.2 kJ)


6. Calculate the enthalpy change for the reaction: P4(s) + 6 Cl2(g)4PCl3(g) H = -2710 kJ if 114.9 grams of chlorine is consumed. (-730.9 kJ)

7. Determine the energy released when 9.73 moles of sulfur dioxide is produced in the reaction: 2

ZnS(s) + 3O2(g) 2 ZnO(s) + 2 SO 2(g) H = -927.54 kJ/mole ZnSa. Is this reaction endothermic or exothermic?

8. Calculate the mass of water produced in the reaction below if 1925.6 kJ of energy is released. (55.4)

2H2(g) + O2(g)2H2O(l) H = -1251.2 kJ/mole O2

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WS H.1 Hess’ Law

1. Calculate the change in enthalpy for each of the following reactions:

A. 2 NO2(g) → N2O4(g)

N2(g) + 2 O2(g) → 2 NO2(g) H = 67.8 kJ

N2(g) + 2 O2(g) → N2O4(g) H = 9.67 kJ

B. C(s) + 2 H2(g) → CH4(g)

C(s) + O2(g) → CO2(g) H = -393.5 kJ

2 H2(g) + O2(g) → 2 H2O(l) H = -571.66 kJ

CO2(g) + 2 H2O(l) → CH4(g) + 2 O2(g) H = 890.37 kJ

C. Sn (s) + 2 Cl2 (g) → SnCl4 (l)

Sn (s) + Cl2(g) → SnCl2(s) H = -325 kJSnCl2 (s) + Cl2 (g) → SnCl4 (l) H = -186 kJ

D. Mn (s) + 02 (g) → MnO2 (s)

MnO2 (s) + Mn (s) → 2 MnO (s) H = -240 kJ2 MnO2 (s) → 2 MnO (s) + 02 (g) H = +264 kJ

E. SnO2 (s) + 2H2 (g) → Sn (s) + 2 H20 (l)

Sn (s) + 02 (g) → SnO2 (s) H = -580.7 kJH2 (g) + 1/2 02 (g) → H20 (l) H = -285.8 kJ

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WS H.2 More Hess’ Law

A. 2 Mg (s) + SiCl4 (l) → Si (s) + 2 MgCl2 (s)

SiCl4 (l) → Si (s) + 2 Cl2 (g) H = +687 kJMg (s) + Cl2 (g) → MgCl2 (s) H = -641 kJ

B. N2 (g) + 2 H2 (g) → N2H4 (l)

H2 (g) + 1/2 02 (g) → H20 (g) H = -242 kJN2 (g) + 2 H20 (g) → N2H4 (l) + 02 (g) H = +534 kJ

C. CH4 (g) + 2 02 (g) → C02 (g) + 2 H20 (l)

C (s) + 2 H2 (g) → CH4 (g) H =-74.8 kJ C (s) + O2 (g) → CO2 (g) H = -393.5 kJ H2 (g) + 1/2 O2 (g) → H2O (l) H = -235.8 kJ

D. 2 C2H6(g) + 7 02(g) → 4 C02(g) + 6 H20(g)

2 C(s) + 3 H2(g) → C2H6(g) H = -84.7 kJC(s) + 02(g) → C02(g) H = -393.5 kJ H2(g) + 1/2 02(g) → H20(g) H = -241.8 kJ

E. 2 N2O3(g) → 2 N2(g) + 3 O2(g)

N2O3(g) → NO(g) + NO2(g) H = 39.7 kJ

½ N2(g) + ½ O2(g) → NO(g) H = 90.4 kJ

½ N2(g) + O2(g) → NO2(g) H = 33.8 kJ

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WS H.3 Even More Hess’ Law

A. C6H4(OH)2 (aq) + H2O2 (aq) C6H4O2 (aq) + 2 H2O (l)

C6H4(OH)2 (aq) C6H4O2 (aq) + H2 (g) H = 177.4 kJ

H2 (g) + O2 (g) H2O2 (aq) H = -191.2 kJ

H2 + ½ O2 (g) H2O (g) H = -241.8 kJ

H2O (g) H2O (l) H = -43.8 kJ

2. Using the equation: O3 + O 2O2, calculate the enthalpy change which occurs when 180 grams of oxygen (O2) is produced.

O3 (g) + Cl (s) O2 (g) +ClO (g) H = -126 kJ O2 (g) + Cl (s) O (g) + ClO (g) H = 268 kJ

3. Calculate the energy released (or absorbed) when 23.5 grams of sodium bromide is reacted in the reaction: ½ Cl2 (g) + NaBr (s) NaCl (s) + ½ Br2 (l)

CaO (s) + Cl2 (g) CaOCl2 (s) H = -110.9 kJ H2O + CaOCl2 (s) + 2NaBr (s) 2NaCl(s) + Ca(OH)2 (s) + Br2 (l) H = = -60.2 kJ Ca(OH)2 (s) CaO (s) + H2O (l) H = 65.1 kJ

4. Determine if the equation :Cu (s) + ½ O2 (g) CuO (s) is exothermic or endothermic.

2 Cu (s) + S (s) Cu2S (s) H = -79.5 kJ S (s) + O2 (g) SO2 (g) H = -297 kJ Cu2S (s) + 2O2 (g) 2CuO (s) + SO2 (g) H = -527.5 kJ

5. In the equation: 4 NH3 (g) + 3 O2 (g) 2N2 (g) + 6 H2O (g), how much energy is released (or absorbed) if 1.5 moles of oxygen is consumed?

4 NH3 (g) + 7 O2 (g) 4 NO2 (g) + 6 H2O (g) H = = 2740 kJ6NO2 (g) + 8NH3 (g) 7N2 (g) + 12 H2O (g) H = -2740 kJ

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6. Considering the equation: 3 Mg (s) + N2(g) Mg3N2(s). What is the enthalpy change if 125.75 grams of Mg3N2 is produced.?

3Mg (s) + 2NH3 (g) Mg3N2 (s) + 3H2(g) H = -371 kJ½ N2 (g) + 3/2 H2 (g) NH3 (g) H = -46 kJ

7. Use this equation to answer the following: Mg (s) + N2 (g) + 3 O2 (g) Mg(NO3)2 (s). How many moles of magnesium were used if 207 kJ of energy was released?

8 Mg (s) + Mg(NO3)2 Mg3N2 (s) + 6 MgO (s) H = -3884 kJ Mg3N2 (s) 3 Mg (s) + N2 (g) H = 463 kJ2MgO (s) 2 Mg (s) + O2 (g) H = 1203 kJ

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WS H.4 Hess’ Law Review Worksheet

1. H2S(g) + 3/2O2(g)H2SO3(l) H =

H2O(l) +SO2(g) H2SO3(l) H = -15.5 kJ S(s) + O2(g) SO2(g) H = -74.3 kJ S(s) + H2O(l) H2S(g) + 1/2O2(g) H = 38.7 kJ

2. C(s) + O2(g) CO2(g) H =

H2(g) + ½ O2(g) H2O(l) H = -571.6 kJ C2H6(g) 2C(s) + 3H2(g) H = 169.4 kJC2H6(g) + 7/2 O2(g) 2CO2(g) + 3H2O(l) H = -3121 kJ

3. H2O(g)H2O(l) H =

H2SO4(l) H2S(g) + 2O2(g) H = 392.5 kJ H2SO4(l) SO3(g) + H2O(g) H = 102.5 kJ SO3(g) + H2O(l) H2S(g) + 2O2(g) H = 345 kJ

4. 2CO2(g) + 2H2O(l) CH3COOH(l) + 2O2(g) H =

C(graphite) + O2(g) CO2(g) H = -861.9 kJ2H2(g) + O2(g) 2H2O(l) H = -1251.2 kJ2C(graphite) + 2H2(g) + O2(g) CH3COOH(l) H = -1069.6 kJ

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5. Fe(s) + CO2(g) FeO(s) + CO(g) H =

Fe2O3(s) + 3CO(g) 2Fe(s) + 3CO2(g) H = -69 kJ3Fe2O3(s) + CO(g) 2Fe3O4(s) + CO2(g) H = -117 kJ Fe3O4 + CO(g) 3FeO(s) + CO2(g) H = -54 kJ

6. Zn(s) + 1/8S8(s) + 2O2(g) ZnSO4(s) H =

Zn(s) + 1/8S8(s) ZnS(s) H = -183.92 kJ2ZnS(s) + 3O2(g) 2ZnO(s) + 2SO 2(g) H = -927.54 kJ2SO2(g) + O2(g) 2SO 3(g) H = -196.04 kJ ZnO(s) + SO3(g) ZnSO 4 (s) H = -230.32 kJ

7. For the reaction: CH2O(g) + H2(g) CH4O(l) (H = ?) ; calculate the energy change when 190 grams of CH2O is reacted.

CH2O(g)+N2(g)+3H2(g)N2H4(l)+CH4O(l)

H = 74 kJ N2H4(l) + H2(g 2NH3(g)

H = -36 kJ N2(g) + 3H2(g 2NH3(g)

H = -92 kJ

8. Calculate the hydrogen produced in the reaction: CH4(g) C(s) + 2H2(g) (H =?) when the enthalpy change for this reaction is 237.5kJ.

C(s) + O2(g)CO2(g)

H = -787 kJ H2O(l) H2(g) + 1/2O2(g)

H = 571.6 kJ CH4(g) + 2O2(g)CO2(g) + 2H2O(l)

H = -1781 kJ


WS 3.6 Energy Conversions

1) Perform each of the following conversions:a. 654 cal to

joules b. 12.9 J to

Calories c.

167 kJ to

Calories d. 99.3

Cal to joules

e. 5.7 X 103 J to

kilojoules f. 326 kJ

to joules

2) In a chemical cold pack, two substances are kept separate by a divider. When the divider is broke, the substances mix and absorb heat from the surroundings. The chemical cold pack feels cold. Is the reaction endothermic or exothermic? Draw an energy diagram showing the relative energies of the reactants and products in the reaction.

3) Determine whether each of the following is exothermic or endothermic. a. Dry ice subliming (changing from a solid directly to a gas)

b. The wax in a candle

melting c. A match

burning


WS 3.7 Specific Heat Problems

1. How many joules of heat are required to raise the temperature of 200 grams of water from 20.0C to 50.0C? (2.51 x 104)

2. If 700 grams of water loses 27.0 kilojoules of heat, what is its change in temperature? (9.22)

3. Some water is heated from 10.0C to 50.0C. During the process, 50.0 kilojoules of heat is added to the water. What is the mass (grams) of water heated? (299)

4. What is the specific heat of an unknown substance, if 950 J of heat raises the temperature of a 20.00 gram sample from 18.0C to 42.0C? (1.98)

5. Hg has a specific heat of 0.139 J/gC. How much heat is required to raise the temperature of a 22.80 g sample from 16.2 C to 32.5C? (51.7)

6. How many kJ of heat are needed to raise the temperature of 1.50 L of water from 20.0C

to 37.0C? (1.07 x 102)

7. The specific heats of three different substances are listed as: Carbon tetrachloride: 0.856 J/gCBenzene: 1.74 J/gCAcetic Acid: 2.05 J/gC

A chemistry student finds that 1.47 kJ of heat raise the temperature of 19.70 grams of an unknown substance by 36.4C. Which of the three substances is the unknown substance?


8. How many kJ is released from a 2.00 L bottle of Surge when it cools from 80.0F (294 K)

to its freezing point? Assume that pop has the same properties as water. (-176)

9. What mass of glass (Cp = 0.749 J/gC) is needed to absorb 5.00 104 J of heat, if it starts at 26C and has a final temperature of 275C? (268)

10. What final temperature will 120.00 grams of benzene at 7.00C have after it absorbs 2.20 kJ of heat? The Cp of benzene is 1.74 J/gC. (17.5)

11. 3.0 kg of osmium metal at 241 K is heated to 394 K. How much heat energy is needed for this? The Cp of osmium is 0.130 J/gC. (6.0 x 104)

12. 14.22 grams of a substance absorbs 1.77 kJ of heat. Its temperature changes from −23.0C

to 31.0C. What is the specific heat of the substance? (2.31)

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WS 3.8 Specific Heat Problems

1) An object with a mass of 19 grams, has a specific heat of 0.59J/g°C. If the temperature of this object changes from 100°C to 125°C, how much heat did the object absorb? (2.8 x 102)

2) If 225 ml of water was cooled from 50°C to 35°C, how much heat was released from the water? (remember 1 ml = 1 g for water) (-1.4 x 104)

3) If a 24.3 grams piece of copper(specific heat = 0.384 J/g°C) at room temperature (22°C) is placed outside to absorb 2600 J of heat, what will the final temperature of the copper piece be? (3.0 x 102)

4) You have a 28.2 g sample of a metal heated to 95.2°C. You drop it into 100 grams of water at 25.1°C. The final temperature of the water is 31.0 °C. Assuming no heat loss to the surroundings nor the calorimeter, calculate the specific heat of the metal. (1.36)

5) A 140.0 gram sample of water at 25°C is mixed with 100.0 grams of a certain metal at

100.0°C. When the temperatures have equalized, the (final) temperature of the mixture is 29.6°C. What is the specific heat of the metal? (0.383)

6) How much heat is required to raise the temperature of a 6.21 gram sample of iron

(specific heat = 0.450 J/g°C) from 25.0 °C to 79.8°C? (153)

7) A sample of granite with a temperature of 50ºC is placed into a coffee cup calorimeter containing 250 grams of water at 23.2ºC. If the final temperature of the water is25.1ºC, what was the mass of the granite sample? The specific heat of granite is 0.790J/gºC. (101)

8) A piece of tungsten metal with a mass 23.8 grams is heated and dropped into 50.0 ml of water at 24.0°C. The final temperature of the system is 26.3°C. What is the initial temperature of the metal? (Tungsten = 0.134 J/gºC) (177.2)


9) What is the final temperature when 33 grams of iron (specific heat = 0.450 J/g°C), at

950°C is dropped into 275 ml of water at 22°C? (34)

10) A 2.8 kg sample of a metal with a specific heat of 0.43 J/g°C is heated to 100.0°C then placed in a 50.0 g sample of water at 30.0°C. What is the final temperature of the metal and the water? (90)

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3.9 Review

1. Would each reaction described below be exothermic or endothermic?a.

Fireworks b.

Ice melting

c. Water condensing

d. A light stick glowing

2. Convert the following units as instructed:a. 1900 calories to

Calories b. 450 calories

to joules

c. 965 joules to calories

d. 12,500 joules to kJ

3. You wish to heat water to make coffee. How much heat (in joules) must be used to raise the temperature of 0.180 kg of water from 15°C to 96°C? (61002)

4. An iron skillet weighing 1.51 kg is heated on a stove to 278°C. If the skillet is cooled to room temperature, 21°C, how much heat energy (in joules) must be removed from the iron? The specific heat of iron is 0.450 J/g°C. (-174,632)

5. If a piece of aluminum with a mass of 3.90 grams and a temperature of 99.3°C is dropped into 10.0 ml of water at 22.6°C, what will be the final temperature of the water. The specific heat of aluminum is 0.903 J/g°C. (28.6)

6. 3.17 kJ of heat is applied to a 96.7 g sample of PCl3 at 31.7°C. What is the final temperature of the sample? The specific heat of PCl3 is 0.874J/g°C. (69.2)

7. An unknown metal with an initial temperature of 75.5ºC is placed in a calorimeter containing 100 ml of water. The temperature of the water changes from 23.9ºC to27.2ºC. If the mass of the metal is 28 grams, what is its specific heat? (1.02)

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8. It takes 78.2 J to raise the temperature of 45.6 grams of lead by 13.3°C. What is the specific heat of lead? (0.129)

9. How many joules are required to raise the temperature of 0.500 kg of liquid water by

24.0°C? How many calories are needed? (50,208; 12,000)


WS 3.10 Review Specific Heat Problems

1) A 15.75-g piece of iron absorbs 1086.75 joules of heat energy, and its temperature changes from 25°C to 175°C. Calculate the specific heat capacity of iron. (0.46)

2) How many joules of heat are needed to raise the temperature of 10.0 g of aluminum from

22°C to 55°C, if the specific heat of aluminum is 0.90 J/g°C? (297)

3) A 36.9 g sample of metal is heated to 100.0 °C, and then added to a calorimeter containing 141.5 g of water at 23.1 °C. The temperature of the water rises to a maximum of 25.2 °C before cooling back down. First, did the water absorb heat or did it release heat? Second, what is the specific heat of the metal? (0.45)

4) To what temperature will a 50.0 g piece of glass raise if it absorbs 5275 joules of heat and its specific heat capacity is 0.50 J/g°C? The initial temperature of the glass is 20.0°C. (231)

5) What is the specific heat capacity of silver metal (in J/g°C) if 55.00 g of the metal absorbs

47.3 calories of heat and the temperature rises 15.0°C? (0.24)

6) A mass of metal (Cp = 1.84 J/g°C) is heated to 120°C and the dropped into a cup containing

100 ml of 25°C water. The final temperature of the mixture is 29°C. What is the mass of the metal sample? (10)

7) A 30.0 g sample of water at 7°C is mixed with 50.0 g of water at 57°C. Calculate the final temperature of the mixture assuming no heat loss to the surroundings. Remember that the heat gained by the cooler water is equal to the heat lost by the warmer water. (38.3)


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