Moles and amount of substance

Carbon nanotubes are cylindrical fullerenes.

Figure 11 represents the structure of a carbon nanotube.

Describe the arrangement of carbon atoms in the nanotube shown in Figure 11.

Metal oxides are produced when metals are heated in air. A student investigated the change in mass when 0.12 g of magnesium was heated in air. Figure 5 shows the apparatus.

The student measured the mass of magnesium oxide produced.

0.12 g of magnesium reacted to produce 0.20 g of magnesium oxide. Calculate the number of moles of oxygen gas (O₂) that reacted. Relative atomic mass (A_r): O = 16

The student repeated the experiment without a lid on the crucible. Suggest why the mass of magnesium oxide produced would be different without a lid on the crucible.

Copper reacts with oxygen to produce copper oxide. 63.5 g of copper produces 79.5 g of copper oxide. Calculate the mass of copper oxide produced when 0.50 g of copper reacts with oxygen. Give your answer to 3 significant figures.

Iron reacts with oxygen to produce an oxide of iron. 0.015 moles of iron reacts with 0.010 moles of oxygen gas (O₂). Determine:

• the formula of the iron oxide produced

• the balanced symbol equation for the reaction.

Balanced symbol equation

A student investigated the temperature change when magnesium was added to copper sulfate solution. This is the method used.

1. Pour 30 cm³ of copper sulfate solution into a polystyrene cup.

2. Measure the temperature of copper sulfate solution every minute for 3 minutes.

3. Add magnesium on the fourth minute.

4. Measure the temperature of the mixture at 5 minutes and then every minute up to 14 minutes.

What is the dependent variable in this investigation?

The student used the results to plot a graph.

Figure 4 shows the graph.

Suggest why the copper sulfate solution was left for four minutes before adding the magnesium.

Complete Figure 4 by:

• drawing a line of best fit through all the points after 7 minutes

• extending the line back to 4 minutes.

The temperature change for the reaction is the temperature difference between the two graph lines at 4 minutes. Determine the temperature change for the reaction. Use Figure 4.

Explain why the temperature of the mixture decreases after 7 minutes.

The student repeated the experiment with an unknown metal Q instead of magnesium. All the other variables were kept the same. The student recorded a smaller temperature change. Suggest the identity of metal Q. Give one reason for your answer.

A copper sulfate solution contained 0.100 moles of copper sulfate dissolved

Calculate the mass of copper sulfate in 30.0 cm³ of this solution. Relative formula mass (M_r): CuSO₄ = 159.5

This question is about elements in the periodic table.

What order did scientists use to arrange elements in early periodic tables?

In the early periodic tables some elements were placed in the wrong groups. Mendeleev overcame this in his periodic table. Give one way Mendeleev did this.

Table 2 shows the boiling points of fluorine, chlorine and bromine.

Explain why the boiling points in Table 2 are low.

Explain the trend in the boiling points in Table 2.

Explain why neon is unreactive. Give the electronic structure of neon in your answer.

How many atoms are there in 1 g of argon? The Avogadro constant is 6.02 × 10²³ per mole. Relative atomic mass (A_r): Ar = 40

Group 2 metal carbonates thermally decompose to produce a metal oxide and a gas.

Give the formula of each product when calcium carbonate (CaCO₃) is heated.

The relative formula mass (M_r) of a Group 2 metal carbonate is 197 Relative atomic masses (A_r): C = 12 O = 16 Calculate the relative atomic mass (A_r) of the Group 2 metal in the metal carbonate. Name the Group 2 metal.

Figure 8 shows the volume of gas produced when a different Group 2 carbonate, W, is heated.

Calculate the gradient of the line in Figure 8 Give the unit.

24 dm³ of gas is produced when one mole of a Group 2 carbonate is heated. Determine the relative formula mass of the Group 2 carbonate W. Use Figure 8