Introduction to Chemical Reactions

Introduction to Chemical Reactions

Section 1

a) Measure 10 ml of calcium chloride solution into the small cup provided.

b) Measure 10 ml of sodium carbonate solution into the small cup provided.

c) Place both cups on the balance and record their combined mass.

d) The combined mass of the cups and solutions is ______grams.

e) DO NOT RESET THE BALANCE!!!

f) DO NOT RESET THE BALANCE!!!

g) Leave one of the cups on the balance and pour the other cup into it. Place the empty cup back on the balance with the full one.

h) What evidence exist that a chemical reaction has taken place?

______

i) Has the mass of the cups and solutions changed significantly?

______

j) Why do you think the result in i) occurred?

______

Have your work checked by the instructor at this time.

Section 2

a) The word equation to describe the reaction you observed is:

Calcium chloride + sodium carbonate yields calcium carbonate + sodium chloride

b) The chemical equation for this reaction is:

CaCl2 + Na2CO3 è CaCO3ê + 2NaCl

c) Reactants are the substances that enter into a chemical reaction. List the reactants shown in the

word equation.

______

d) Products are the substances that are produced in a chemical reaction. List the products shown in word equation.

______

e) List the reactants shown in the chemical equation.

______

f) List the products shown in the chemical equation.

______

Have your work checked by the instructor at this time.

Section 3- Calculate the formula mass for the following formulas.

CaCl2 Na2CO3

Number of atoms / Mass Number / Number of atoms / Mass Number
Ca / Na
Cl / C
TOTAL / O
TOTAL

CaCO3 2NaCl

Number of atoms / Mass Number / Number of atoms / Mass Number
Ca / Na
C / Cl
O / TOTAL
TOTAL

Have your work checked by the instructor at this time.

Section 4

a) List the correct formula mass under each formula. On the next line list the combined formula mass for the reactants and the combined formula mass for the products.

CaCl2 + Na2CO3 è CaCO3ê + 2NaCl

______+ ______è ______+ ______

______è ______

b) Does this equation represent what you observed?

______

c) Does this equation show conservation of mass?

______

d) How many units of NaCl are needed to show “balance” between reactants and products ?

______

Have your work checked by the instructor at this time.

Section 5

a) Fill in the chart showing the total number of each atom on the reactant side of the equation and on the product side of the equation.

CaCl2 + Na2CO3 è CaCO3ê + 2NaCl

Reactants / è / Products
Ca / Ca
Cl / Cl
Na / Na
C / C
O / O

b) How does the number of atoms on the reactant side of the equation compare to the number of

atoms on the product side of the equation?

______

c) How does this show conservation of mass?

______

Have your work checked by the instructor at this time.

Section 6

Safety notice- The person blowing carbon dioxide into the test tube MUST be wearing goggles!

a) Pour 15 ml of lime water into the corner of a Ziploc bag.

b) Put a straw into the liquid and seal the bag around the straw.

c) Hold the bag up to the light. Observe the present clarity of the solution.

d) Vent carbon dioxide into the solution by GENTLY blowing through a straw into the solution.

e) Hold the bag up to the light again. Repeat step c until a definite change is observed.

f) What indication is there that a new substance has been formed?

______

Have your work checked by the instructor at this time.

Section 7

a) The word equation to describe the reaction you observed is:

Calcium hydroxide + carbon dioxide yields calcium carbonate + water

b) The chemical equation for this reaction is:

Ca(OH)2 + CO2 è CaCO3ê + H2O

c) Reactants are the substances that enter into a chemical reaction. List the reactants shown in the

word equation.

______

d) Products are the substances that are produced in a chemical reaction. List the products shown in word equation.

______

e) List the reactants shown in the chemical equation.

______

f) List the products shown in the chemical equation.

______

Have your work checked by the instructor at this time.

Section 8- Calculate the formula mass for the following formulas.

Ca(OH)2 CO2

Number of atoms / Mass Number / Number of atoms / Mass Number
Ca / C
O / O
H / TOTAL
TOTAL

CaCO3 H2O

Number of atoms / Mass Number / Number of atoms / Mass Number
Ca / H
C / O
O / TOTAL
TOTAL

Have your work checked by the instructor at this time.

Section 9

a) List the correct formula mass under each formula. On the next line list the combined formula weight for the reactants and the combined formula weight for the products.

Ca(OH)2 + CO2 è CaCO3ê + H2O

______+ ______è ______+ ______

______è ______

b) How does the formula mass of the products compare to the formula mass of the reactants?

______

c) Does this equation show conservation of mass? Be prepared to explain your answer.

______

Have your work checked by the instructor at this time.

Section 10

a) Fill in the chart showing the total number of each atom on the reactant side of the equation and on the product side of the equation.

Ca(OH)2 + CO2 è CaCO3ê + H2O

Reactants / è / Products
Ca / Ca
C / C
O / O
H / H

b) How does the number of atoms on the reactant side of the equation compare to the number of

atoms on the product side of the equation?

______

c) How does this show conservation of mass? Be prepared to explain your answer.

______