INTRODUCTION TO CHEMICAL EQUATIONS1. Classify each change in the following table as either chemical or physical.

Explain your classification.

Change Chemical or Physical?

Explanation

A sheet of paper is crumpled into a ballA sheet of paper is set on fire and burns to ashesSteel wool is placed in a glass of salty water. The steel wool rusts.A sheet of flexible colourless plastic is left outside and becomes yellow and brittle over time.A teaspoon of white sugar dissolves in a glass of warm water.Vinegar is poured over a teaspoon of baking soda. The white baking soda powder fizzes, and bubbles formA red-hot nail is inserted into a large block of ice. Steam is formed as the nail contacts the block. Water flows away from the nail.

2. Identify the states of matter, reactants, products and coefficients in the following chemical reactions.

a. ZnCl2 (aq) Zn (s) + __ Cl2(g)

b. 2 RbNO3 (aq) + BeF2(aq) __ Be(NO3)2(aq) + 2 RbF(s)

c. S8(s) + 8 H2(g) 8 H2S(g)

d. LiCl(aq) + __ Br2(g) __ LiBr(aq) + __ Cl2(g)

3. How many atoms of each element are present in each of the followinga. H2SO4

b. Ba(NO3)2

c. 2 MgCl2d. 3 Al2(SO4)3

e. 2 NaCl + 3 K2Of. 3 KNO3 + Al2(SO4)3

g. HNO3 + 2 H2O h. NH4Cl + H3PO4

4. State the Law of Conservation of Mass.

5. Which of these equations are skeleton equations and which are balanced equations?

a. H2SO4 + 2 KOH 2 H2O + K2SO4

b. C10H8 + O2 CO2 + H2O

c. 2 HI H2 + I2

d. HCl + Al H2 + AlCl3

e. N2 + 3 F2 2 NF3

f. 2 KClO3 2 KCl + 3 O2

g. Mg + Br2 MgBr2