Using the equation from Example 1, calculate the mass of H₂O_(g) produced by burning 100g of methane in excess oxygen.

Using the equation from Example 3, calculate the mass of MgO_(s) produced by burning 30.0g of magnesium in excess oxygen.

Iron filings will burn in sulfur to produce iron II sulfide. Write an equation for this reaction and then calculate the mass of iron II sulfide produced when 26.0g of iron reacts with excess sulfur.

Question 4:

If calcium carbonate solid is heated strongly it decomposes. What mass of carbon dioxide gas would be produced if 10g of calcium carbonate was heated? (Write an equation first.)

The Hindenburg airship exploded when the hydrogen gas it contained sparked with oxygen in air. Write an equation for this reaction. If the airship contained 9 kg of hydrogen, what mass of oxygen would be consumed in the reaction?

When sodium metal is dropped into water, a vigorous reaction occurs. Hydrogen gas is evolved and a solution of sodium hydroxide (NaOH) is formed.

1. Write the balanced equation for this reaction.
2. If 2.3g of sodium are put into water, how many moles of hydrogen will be produced?
3. What will be the mass of this hydrogen?

When copper II oxide is heated in the presence of hydrogen gas, the products are copper metal and water vapour.

1. Write the balanced equation for this reaction.
2. How many grams of copper metal will be obtained from the heating of 4.0g of copper oxide with an excess of hydrogen gas?

In the process of photosynthesis carbon dioxide and water are combined to form glucose, C₆H₁₂O₆. The extra oxygen atoms come out as oxygen gas.

1. What masses of CO₂ and H₂O are required to produce 500g glucose?
2. What mass of oxygen is produced?
3. Do the masses of the reactants equal the masses of the products?

An average human being uses about 500 kg (1 kg = 1000 g) of oxygen per year in an extremely complex series of reactions, one of which is the reverse of the equation in Question 8, above.

1. How many moles of oxygen are contained in 500 kg of oxygen?
2. If one hectare of grassland produces 2800 kg of oxygen per year, how many people (considering oxygen requirements alone) can one hectare of grassland support?

Question 10:

Methane (CH₄) burns in air to produce water. If sufficient oxygen is present CO₂ is another product. If insufficient oxygen is present CO is another product.

1. Write balanced equations for these reactions.
2. Calculate the mass of oxygen required to burn 160 grams of methane in each case.

 

And now for the grand finale:

2.5g of barium hydroxide crystals are thoroughly mixed into a solution of copper (II) chloride. The concentration of the solution before mixing is 0.1M, its volume is 100mL. (Cheat to make the maths a wee bit simpler and assume the added crystals add nothing to the volume. In reality this is close to true.)

1. What is the concentration of each ion after mixing? 
2. What is the mass of the resulting precipitate?