DAY 3 – Answers
Chemical Reactions and (HT) Balancing Equations
KEY
WORDS
Chemical Reaction  Reactants  Products  Mass Conservation 
Balanced 
Question
1
What does a word equation tell you?
Answer:
What happens to chemicals during a chemical reaction
2
What substances are on the left side of the equation?
Answer:
3
Answer:
4
Answer:
5
Answer:
6
Answer:
Reactants
What substances are on the right side of the equation?
Products
What must the total mass of reactants always equal?
Stays the same
What happens to the number of atoms in a chemical equation?
Stays the same
How many of each type of atom are present in CO2?
1 carbon
2 oxygen
7
Describe what has happened to the atoms in this reaction: H2 + O2  H2O
Answer:
1 molecule of 2 hydrogen atoms + 1 molecule of 2 oxygen atoms react to
produce 1 molecule of water containing 1 atom of oxygen + 2 hydrogen atoms
8
Balance the equation in Question 7
Answer:
2H2 + O2  2H2O
9
Answer:
Balance the following equation: Al + O2  Al2O3
2Al + 3O2  2Al2O3
10
Answer:
Balance the following equation: Cr + HCl  H2 + CrCl3
2Cr + 6HCl  3H2 + 2CrCl3
DAY 4
Limestone and Building Materials
KEY
WORDS
Limestone  Calcium carbonate  Thermal decomposition  Calcium oxide 
Calcium hydroxide  Cement  Mortar  Concrete  Acid reactions 
Question
1
Give at least 5 uses for limestone
Answer:
2
What is the chemical formula for calcium carbonate (limestone)?
Answer:
3
In a lime kiln, calcium carbonate is heated to make what two products?
Answer:
4
Give the formula for calcium oxide (lime or quicklime)
Answer:
5
When water is added to quicklime what product is made?
Answer:
6
Name the products when copper carbonate is thermally decomposed
Answer:
7
What substance is powdered limestone mixed with to make cement?
Answer:
8
What is the difference between mortar and concrete?
Answer:
9
What is the chemical test for carbon dioxide gas?
Answer:
10
Answer:
Why are there concerns over the production of limestone?