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3.
Calculate the Mr for the following substances. Show your working where possible.
1. Water (H2O)
2. Carbon dioxide (CO2)
3. Sodium chloride (NaCl)
4. Magnesium hydroxide (Mg(OH)2)
5. Aluminium sulfate (Al2(SO4)3)
When you know that your answers are correct copy the questions and answer into your book.
Calculate the mass of magnesium oxide (MgO) produced when 12g of magnesium
burns completely in oxygen.
2Mg + O2 → 2MgO
Copy this into your book showing full working.
Do this for all further questions.
Iron reacts with copper(II) sulfate solution. Calculate the mass of copper produced if 5.6g of iron is used.
Fe + CuSO4 → FeSO4 + Cu
What mass of hydrogen gas (H2) is needed to react with oxygen to produce 36g of
water?
2H2 + O2 → 2H2O
Calculate the mass of carbon dioxide produced when 32g of methane (CH4) is burned completely.
CH4 + 2O2 → CO2 + 2H2O
Moles of H2 =
Moles of O2
If we consider H2 we need to divide the moles of H2 by 2 to work out the moles of O2 needed =
This is more than the moles of O2 available so oxygen is the
Moles of H2O = moles O2 x 2 from the balanced equation =
Mass of water = moles x RFM =
limiting reagent is
Mass if ZnCl2 produced =
Limiting reagent =
Mass of NaCl produced =
Limiting reagent is
Mass of MgSO4 produced =