type of chemical reactions - garzzillo...
Post on 04-Feb-2021
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Type of Chemical Reactions • Combination • Decomposition • Single Replacement • Double Replacement • Combustion
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Reaction Types There are five reaction types that have to be
identified and balanced 1. Combination (or synthesis) 2. Decomposition 3. Single Replacement 4. Double replacement 5. Combustion
In an experiment we would use multiple observation to identify reactions
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Combination (Synthesis) Two or more substances react to form a
single new substance General equation: A + B à AB
Example: Mg(s) + O2(g) à MgO(s)
To determine products, reactant must be known (or vise versa)
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Decomposition Reaction A single compound breaks down into two
or more simpler products
General equation: AB à A + B Example: HgO(s) à Hg(l) + O2(g)
Reverse of synthesis
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Predicting Products Synthesis:
Combine the two elements together in a single chemical formula.
Be sure to check charges (OXIDATION NUMBERS!!) Cross-over when necessary (if it is IONIC!)
Decomposition: Separate the given compound into its elements. Don’t forget about DIATOMIC elements!
H2, N2, O2, F2, Cl2, Br2, I2
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Examples (Balance them too!) Mg + O2 à MgO Questions to ask yourself:
1. Are the charges balanced? Yes 2. Are the metals ok? Yes 3. Are the non-metals ok? No
What do we need to add?
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Mg + O2 à MgO ______ Mg ______ Mg ______ O ______ O
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Single Replacement One element replaces a second element
in a compound
General equation: A + BC à AC + B Must conform to the activity series
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Ex: Cu(s) + AgNO3(aq) à Cu(NO3)2(aq) + Ag(s)
Whether or not an element will replace another element depends on its REACTIVITY
Copper (Cu) is more reactive than silver (Ag), therefore copper will replace silver in the reaction, causing silver to precipitate.
Single Replacement
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Activity Series for Metals A list that ranks metals
from most reactive to least reactive
The activity series
answers the question, “Can one metal replace a metal inside a compound?”
If the metal seeking to replace another metal is LESS reactive then the reaction will NOT happen
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Examples of how activity series work
Ca + AlCl3 à CaCl2 + Al Calcium is more reactive than aluminum Therefore, the reaction occurs
2AlN + 3Mg à Mg3N2 + 2Al Mg is more reactive than Al Reaction will occur
Cu + Na2O à NO REACTION Copper is not more reactive than sodium The reaction does not occur
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Double Replacement An exchange of positive ions between two
compounds In order to take place, one of the new
compounds formed MUST leave the solution Either as a gas or as a precipitate
General equation: AB + CD à CB + AD Ex: FeS + 2HCl à H2S + FeCl2
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Predicting Products 1. Swap the positive ions (Usually metals) 2. Figure out the charges and criss cross to
get the formula
AlPO4 + FeI3 à AlI3(aq) + FePO4(s)
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Examples Na2S(aq) + Cd(NO3)2(aq)à 2NaCN(aq) + H2SO4(aq)à 3NaOH(aq) + Fe(NO3)3(aq)à
3Ba(NO3)2(aq) +2H3PO4(aq)à (Barium Phosphate is a precipitate)
CdS(s) + 2NaNO3(aq)
2HCN(g) + Na2SO4(aq)
Fe(OH)3(s) + 3NaNO3(aq)
Ba3(PO4)2(s) + 6HNO3(aq)
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Combustion An element or a
compound reacts with oxygen (O2), often producing energy in the form of heat and light
Hydrocarbons often combust
Fossil fuels, good source of energy
Products are often water and carbon dioxide (CO2)
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Combustion Practice
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