Chapter 7: Chemical Reactions Review Sheet Name:

1) In a chemical reaction reactants undergo a change to become products

2) A representation of a reaction in formulas is called a chemical equation

3) In the law of conservation of mass the mass of reactants must be equal to the mass of

products in a reaction.

4) To make the atoms of reactants equal to the atoms of products in an equation, you must balance

a reaction.

5) Balance these equations:

a) 4 Fe + 3 O2 2 Fe2O3 synthesis

b) WO3 + 3 H2 W + 3 H2O single replacement

c) 2 PbS + 3 O2 2 PbO + 2 SO2

d) Na2SO4 + 2 KCl 2 NaCl + K2SO4 double replacement

e) SiO2 + 2 C SiC + 2 CO

f) Al(OH)3 + 3 HCl AlCl3 + 3 H2O double replacement

g) 2 Cr2O3 + 3 Si 4 Cr + 3 SiO2 single replacement

h) CaCO3 CaO + CO2 balanced decomposition

6) Classify the reactions above by writing the reaction type on the line provided. (No line = no type)

7) What type of reaction only produces one product? synthesis

8) What type of reaction has only one reactant? decomposition

9) What type of reaction has a single element reacting with a compound and replacing an element in that

compound ? single replacement

10) What type of reaction produces heat and light and frequently produces CO2and H2O as products?

combustion

11) What type of reaction involves two compounds (usually dissolved in water) which switch their ion

pairs? Double replacement

12) Calculate the molar mass of the following compounds: (UNITS!!!)

a) NaCl 58.44 g

b) CaSO4 136.14 g

c) Al(OH)3 78.00 g

d) C6H12O6 180.16 g

e) (NH4)2CO3 96.09 g

f) FePO4 150.82 g

13) Calculate the number of atoms in 4.25 moles of Na. 4.25 mol Na x 6.02 x 10 23 atoms = 2.56 x 1024 atoms

1 mol

14) How many moles are in 3.45 x 1021 molecules H2O?3.45 x 1021 molecules H2O x 1 mole = 0.00573 mol H2O

6.02 x 1023 molecules

15) How many moles do you have with 8.90 x 1023 formula units of LiCl?8.90 x 1023 formula units LiCl x 1 mole = 1.48 mol LiCl

6.02 x 1023 f. units

16) What is the mass of 9.00 moles of Li? 9.00 mol Li x 6.941 g = 62.5 g 1 mole

17) How many moles are in 15.0 g of Sulfur? 15.0 g S x 1 mole = 0.468 mol S32.065 g

18) How many atoms would you have in 1.24 grams of Carbon?1.24 g C x 1 mole x 6.02 x 10 23 atoms = 6.22 x 1022 atoms C

12.0107 g 1 mol

19) What is the mass of 2.66 x 1022 molecules of CO2?2.66 x 1022 molecules CO2 x 1 mole x 44.01 g = 1.94 g CO2

6.02 x 1023 molecules 1 mole

20) Would the reaction of Na + MgCl2 occur? Yes Why or why not? Sodium is more reactive

than magnesium so it will replace the magnesium in the compound.

21) Complete the reaction of Li + Na2SO4 Li2SO4 + Na

22) Would the reaction of Cu + AlCl3 occur? No Why or why not? The copper is not more

reactive than aluminum so it cannot replace the aluminum in the compound

23) What would be the most likely products of the reactants NaOH + BaSO4 be?

a) NaBa & H2SO5 b) NaSO4 & BaOH c) Na2SO4 & Ba(OH)2 d) NaOH & BaSO4

24) If a reaction gives off energy to its surroundings, it is classified as exothermic

25) If a reaction absorbs energy from its surroundings, it is classified as endothermic

26) Is this reaction endo or exothermic? 2Na + 2H2O 2NaOH + H2 + 239.87 kJ exothermic

27) If this reaction endo or exothermic? N2 + O2 + 179.91 kJ 2NO endothermic

28) Reaction rates are affected by : temperature , concentration ,

stirring , surface area & catalysts

29) What substance can increase the rate of a reaction but is not changed chemically in the process and

can be used repeatedly? catalysts

30) Collisions of particles can be increased by stirring & increasing temperature