Moles and amount of substance

Copper can be made by reacting copper oxide, CuO, with carbon, C.

When 2.00 g of copper oxide reacts with 1.00 g of carbon, copper oxide is the limiting reactant.

Explain the effect of a limiting reactant on a reaction.

Calculate the number of moles in 2.00 g of copper oxide and 1.00 g of carbon.

Give your answers to 3 decimal places.

Relative atomic mass (A_r): C = 12.0 O = 16.0 Cu = 63.5

Use your answers in part (b) to explain why copper oxide is the limiting reactant.

The number of moles in a different mass of copper oxide is 0.045.

Calculate the maximum mass of copper, Cu, that can be made from 0.045 moles of copper oxide.

Give your answer to 2 significant figures.

Relative atomic mass (A_r): Cu = 63.5

This is the symbol for helium.

What is the mass of one atom of helium?

The Avogadro constant = 6.02 × 10²³

A 3.32 × 10^–24 g

B 6.64 × 10^–24 g

C 1.51 × 10²³ g

D 3.01 × 10²³ g

Describe the difference between a strong acid and a weak acid.

Hydrochloric acid, HC l (aq), is an example of a strong acid.

The graph shows the pH of a dilute hydrochloric acid solution at different concentrations.

Concentration of dilute hydrochloric acid solution (mol/dm³)

Write the formula of the ion that gives the dilute hydrochloric acid solution the pH shown on the graph.

The pH of the dilute hydrochloric acid solution can be measured using either universal indicator or a pH meter.

Explain which method would be better to use for measuring the pH shown on the graph.

Describe how the pH changes with the concentration of dilute hydrochloric acid solution on the graph.

As the concentration of the dilute hydrochloric acid solution increases by a factor of ten, the pH of the solution decreases by one.

Use data from the graph to show that this statement is true.

Calculate the mass of hydrochloric acid, HCl, in 100 cm³ of solution that gives a pH 1.5. (e)

Use data from the graph.

Give your answer to 2 significant figures.

Relative molecular mass (M_r): HCl = 36.5

Calcium is a metal found in Group 2 of the Periodic Table.

Draw the arrangement of electrons in an atom of calcium.

Calcium is a metal which can conduct electricity.

Describe the structure and bonding in a metal and explain why metals can conduct electricity.

You can include a diagram in your answer.

Calcium reacts with water to form a solution of calcium hydroxide, Ca(OH)₂, and hydrogen.

Write the balanced symbol equation for the reaction of calcium with water.

Include state symbols in your equation.

A solution of calcium hydroxide is also called limewater.

Name the gas limewater is used as a test for.

Calculate the number of moles in 1.88 g of calcium hydroxide.

Give your answer to 2 significant figures.

Relative atomic mass (A_r): H = 1.0 O = 16.0 Ca = 40.1

Use your answer to part (d)(i) to calculate the concentration of calcium hydroxide in the solution formed.

Give your answer in mol / dm³.

Concentration of solution =........ mol / dm³

A student adds an excess of dilute hydrochloric acid, HC l, to a solution of calcium hydroxide, Ca(OH)₂.

Write the balanced ionic equation for the reaction of dilute hydrochloric acid and a solution of calcium hydroxide.

Describe and explain how the pH of the solution of calcium hydroxide changes as the dilute hydrochloric acid is added until it is in excess.

The mole is a unit of measurement used in chemistry for the amount of a substance.

Define the term mole.

Iron, Fe, reacts with steam, H₂O. An oxide of iron and hydrogen, H₂, are made.

The oxide of iron has the formula Fe_xO_y where x and y are whole numbers.

In a reaction 1.67 g of iron, Fe, reacts with 0.72 g of steam, H₂O. 0.08 g of hydrogen, H₂, are made.

Calculate the number of moles of iron, steam and hydrogen.

Give your answers to 2 decimal places.

The relative atomic mass, A_r, of H is 1.0, of O is 16.0 and of Fe is 55.8

Look at the reaction equation. It shows the formation of 1 mole of the oxide of iron, Fe_xO_y.

Use your answers to (b)(i) to balance the reaction equation and work out the formula of the oxide of iron, Fe_xO_y.

A student investigates how to make a sample of a pure salt.

His method is shown in Fig. 14.1.

React an excess of copper oxide with 50 cm³ dilute hydrochloric acid. Stage 1

Stage 2 Heat the solution from Stage 1.

Copper oxide is an insoluble compound that neutralises dilute hydrochloric acid.

Name the type of insoluble compound that neutralises an acid to form a salt and water.

Dilute hydrochloric acid is a hazardous chemical.

Describe one safety precaution the student should take when using dilute hydrochloric acid.

Stage 1 uses an excess of copper oxide.

Give a reason why.

Calculate the number of moles of copper oxide, CuO, in 0.500 g.

Give your answer to 3 significant figures.

Use your answer to (d)(i) and the balanced symbol equation to explain why the copper oxide is in excess.

Another student thinks that the method in Fig. 14.1 will not make pure copper chloride.

Explain why this student is correct.

What is the mass of 2 moles of calcium hydroxide?

A 148.2 g

B 164.1 g

C 220.1 g

D 328.2 g

Aluminium, phosphorus and magnesium are all in Period 3 of the Periodic Table.

Aluminium has an atomic number of 13 and mass number of 27.

Describe the nucleus of an aluminium atom in terms of sub-atomic particles.

What is the overall charge on the nucleus of an atom of aluminium?

Which sub-atomic particles surround the nucleus?

Phosphorus has a higher atomic number and a higher mass number than aluminium.

A student says that phosphorus must be an isotope of aluminium because it has a different number of neutrons.

Is the student correct?

Tick (✓) one box.

Explain your answer.

Phosphorus can react with oxygen to form oxides. One oxide of phosphorus is called phosphorus pentoxide.

Phosphorus pentoxide has the molecular formula P₄O₁₀.

What is the empirical formula of phosphorus pentoxide?

Aluminium oxide and phosphorus pentoxide have different types of bonding.

The boiling point of aluminium oxide is 2977 °C.

The boiling point of phosphorus pentoxide is 360 °C.

What conclusion can you make about the type of bonding in each oxide?

Explain your answers.

The student is given a sample of the metal magnesium and a solution of an unknown nitrate of metal M, MNO₃(aq).

The student does an experiment to identify metal M.

The student weighs the magnesium. Then the student adds the magnesium to the solution of the metal nitrate.

A displacement reaction takes place forming metal M:

The student separates the metal M and then weighs metal M.

Look at the student’s results: Mass of magnesium = 0.729 g Mass of metal M = 6.476 g

Calculate the moles of magnesium used in the experiment.

Calculate the relative atomic mass of metal M.

Give your answer to 3 significant figures.

Use your answer from (d)(ii) and the Periodic Table to identify the metal M.

Carbon is an element which can form a very wide range of compounds.

This is partly due to the number of bonds that a carbon atom can form.

State the type and maximum number of bonds that a carbon atom forms.

Maximum number of bonds........

Hex-1-ene is a carbon-based compound with the formula C₆H₁₂.

20.0 g of hex-1-ene is burned in oxygen. Carbon dioxide and water are made. Look at the equation for this reaction.

Calculate the number of molecules in 20.0 g of hex-1-ene.

Avogadro’s constant = 6.02 × 10²³ mol^–1

Give your answer to 3 significant figures.

Number of molecules of C₆H₁₂ =........

Hex-1-ene was burned using a spirit burner in the laboratory.

The diagram shows the spirit burner.

Burning 20.0 g of hex-1-ene should produce 62.9 g of carbon dioxide.

The actual mass of carbon dioxide produced in the reaction was 48.4 g.

What conclusion can be made about the mass of oxygen available for combustion?