PCM. Changes in Matter Benchmark 1

Explain chemical changes in terms of the breaking of bonds and the rearrangement of atoms

to form new substances.

Atom

Molecule

Ion

Bond

Reactant

Product

Key concepts

Conservation of mass

Rate of reaction—temperature, surface area, concentration

Specific chemical reactions—burning paper or wood, rusting iron, formation of sugars duringphotosynthesis

Key concepts

Examples of chemical changes

Real-world contexts

Question One

Question Two

Question Three

Question Four

Which of the following is a correct chemical equation?

a) NaOH + HCl N Cla + HCC**

b) NaOH + HCl NaCCl + CH C

c) NaOH + HCl N Cla + CHCC

d) NaOH + HCl CN Cl + a HCC

e) NaOH + HCl NaCClC + HCCC

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For all incorrect answers: the exact type of atom as well as the exact number of those atoms must be equal on both sides of the arrow. The number and type of atoms must be the same in the reactants and products!!

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In a chemical reaction, chemicals called ________ are combined to form new compounds called________

a. Atoms; molecules

b. Ions; bonds

c. Reactants; products

d. Electrons; protons

e. Ionic; covalent

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Which reaction would be the fastest? One which has:

a) High concentrations of reactants, high temperature, catalysts

b) Low concentrations of reactants, high temperature, catalysts

c) High concentrations of reactants, low temperature, no catalyst

d) High concentrations of reactants, high temperature, no catalyst

e) Low concentrations of reactants, low temperature, no catalyst

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In nature, the rate of a reaction depends on a variety of things. The more reactants there are the more often collisions will take place speeding the reaction. The higher temperatures will cause molecules to move faster causing more collisions which speeds a reaction. If a catalyst is present, it “manages” the reaction and has the ability to make reactions happen more quickly

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Which one of the following is NOT an example of a

chemical reaction?

a) Burning paper

b) Rusting iron

c) Formation of sugars during photosynthesis

d) Explosion of TNT

e) Boiling water into steam

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A. Burning paper results in new products being made, smoke, carbon dioxide so it’s a chemical reaction

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B. Rusting iron results in iron oxide being made from iron, thus a new product is made therefore it’s a chemical reaction

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C. In photosynthesis, sugars are made from carbon dioxide and water. A new product is made, sugar, so therefore this is a chemical reaction

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D. In an explosion of TNT, the TNT no longer exists, new products are made therefore it’s an example of a chemical reaction

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