Calculations Involving Masses (Edexcel GCSE Chemistry)

Higher Only

How many moles are present in 9 kg of glucose, C₆H₁₂O₆?

Relative formula mass (M_r):       C₆H₁₂O₆ = 180

Higher Only

What is the mass of 0.25 moles of hydrated copper(II) sulfate, CuSO₄.5H₂O?

Relative formula mass (M_r):  H₂O = 18  CuSO₄ = 160

Higher Only

Nitrogen and hydrogen react together to make ammonia.

N₂ + 3H₂  → 2NH₃

If 2.0 g of hydrogen is added to 12.0 g of nitrogen which substance is the limiting reactant and how much of the excess reactant remains?

Relative atomic masses (A_r): H = 1    N = 14

A solution of CuSO₄ has a concentration of 35 g dm^-3.

What mass of CuSO₄ would there be in 250 cm³ of the solution?

What is the relative formula mass of butene, C₄H₈ ?

(relative atomic masses: H=1, C=12)

Iron is a metal

Describe the structure and bonding of iron.

Higher Tier Only

The relative atomic mass of iron is 56.

Calculate the number of atoms in 28 g of iron.

(Avogadro constant = 6.02 x 10²³)

Higher Tier Only

4.48 g of iron combines with 1.92 g of oxygen to form an oxide of iron.

[3]

[1]

 Iron reacts with halogens to form iron(III) halides.

The balanced equation for the reaction of iron with chlorine is:

2Fe (s) + 3Cl₂ (g) → 2FeCl₃ (s)

Calculate the mass of iron chloride formed when 14 g of iron reacts with excess chlorine.

Give your answer to 1 decimal place.

(relative atomic masses: Fe = 56, Cl = 35.5)

Chemistry Only

Figure 1 shows the structure of a molecule.

Figure 1

Name the molecule.

State the empirical formula of the molecule.

Calculate the relative formula mass of the molecule.

(relative atomic masses: C = 12, H = 1, O = 16)

Higher Tier Only

Calculate the number of moles in 75.14 g of the molecule.

Give your answer to 3 significant figures.

The equipment shown in Figure 1 can be used to work out the empirical formula of magnesium oxide.

Figure 1 

Describe how you would use the equipment in Figure 3 to work out the mass of oxygen that will react with 6.0 g of magnesium to make magnesium oxide.

A scientist found that when 6.0 g of magnesium completely reacted the magnesium oxide formed had a mass of 10.0 g.

Use this information to prove that the empirical formula of magnesium oxide is MgO.

(relative atomic masses: Mg = 24, O = 16)

Higher Tier Only

Calculate the number of moles in 9.4 g of magnesium oxide.

Give your answer to 1 decimal place.

Higher Tier Only

Calculate the number of atoms combined in one mole of magnesium oxide.

(Avogadro constant = 6.02 x 10²³)

Copper sulfate solution was added to sodium hydroxide solution.

The copper sulfate solution was prepared by dissolving 4.34 g of solid copper sulfate in water and making the volume up to 250 cm³.

Calculate the concentration of the copper sulfate solution in g dm⁻³.

Give your answer to three significant figures.

Balance the symbol equation for this reaction:

CuSO₄ (aq) + ……NaOH (aq) → Cu(OH)₂ (s) + Na₂SO₄ (aq)

Why is this a precipitation reaction?

7.98 g of copper sulfate reacts with 4.0 g of sodium hydroxide to form 4.88 g of copper hydroxide.

Calculate the mass of sodium sulfate made.

A teacher demonstrates the thermite reaction, a highly exothermic reaction between aluminium and iron(III) oxide that produces molten iron.

Explain why the iron produced is molten.

Higher Tier Only

The symbol equation for the reaction is Fe₂O₃ + Al → Al₂O₃ + Fe

Name the substance that is:

[1]

[1]

Higher Tier Only

Calculate the number of moles in 8 g of iron oxide.

(relative atomic masses: Fe = 56, O = 16)

Higher Tier Only

The teacher used 10 g of aluminium.
The relative atomic mass of aluminium is 27.

Show that the aluminium is in excess.