Reactivity of metals

This question is about metals and their reactions with acids.

Place ticks () in boxes to show which elements in the table are metals.

Use the periodic table to help you answer this question.

Three equal sized pieces of the metals E, F, G and H are put into separate test tubes containing equal volumes of dilute sulfuric acid.

The results in Figure 6 show the test tubes after half a minute.

Arrange the metals E, F, G and H in order of reactivity.

The bubbles that form are hydrogen.

Which row of the table shows the test and result that confirm the gas is hydrogen?

When zinc reacts with very dilute nitric acid, zinc nitrate is formed.

The formula of zinc nitrate is Zn(NO₃)₂

Calculate the relative formula mass of zinc nitrate, Zn(NO₃)₂

(relative atomic masses: Zn = 65, N = 14, O = 16)

relative formula mass =_........

A student investigates the reaction between a metal and a dilute acid using the apparatus shown in Figure 7.

Cotton wool is placed in the top of the apparatus as shown, to stop any acid from spraying out.

The total mass of the apparatus is shown at the start of the reaction and after the reaction has ended.

start of reaction end of reaction

Figure 7

State two ways the student would know that the reaction has ended.

An investigation was carried out on the reactivity of four metals, D, E, F and G.

Equal sized pieces of these metals were placed in excess dilute hydrochloric acid and left for three minutes.

Figure 6 shows the observations of the reactions for metals D, E and F.

The order of reactivity for these metals is shown in Figure 7.

most reactive
least reactive

Figure 7

Use the information in Figure 6 and Figure 7 to suggest the observations that would be made for metal G.

The dilute hydrochloric acid used in this reaction is a strong acid.

Explain the meaning of the terms dilute and strong acid.

dilute

strong acid

The formula of lead ethanoate is Pb(CH₃COO)₂.

Calculate the number of atoms that combine together to form 16.25 g of lead ethanoate.

(relative atomic masses: H = 1.00, C = 12.0, O = 16.0, Pb = 207

Avogadro number = 6.02×10²³)

number of atoms =_........

Figure 8 shows part of the reactivity series of metals.

Which metal reacts when added to cold water?

A student investigates the reactivity of four different metals.

The student adds an equal‑sized piece of each metal to separate test tubes containing dilute hydrochloric acid.

The student’s observations for zinc and copper are recorded in Figure 9.

Use the information in Figure 8 and in Figure 9 to predict the observations for the reactions of magnesium and of iron with dilute hydrochloric acid.

magnesium

iron

When metals react with acids, hydrogen gas is produced.

Describe the test to show that the gas is hydrogen.

When magnesium reacts with hydrochloric acid, magnesium chloride and hydrogen are formed.

Complete the balanced equation for the reaction.

Mg +_........ HCl MgCl₂ +_........

*(c) There are three common methods of obtaining metals from the Earth’s crust:

• mine the pure metal

• mine the metal ore and heat it with carbon

• mine the metal ore and electrolyse the molten compound.

The method used to obtain a metal is linked to its position in the reactivity series of metals.

Aluminium, gold, iron, and silver are some commonly used metals.

Use the reactivity series in Figure 8 to state and explain the method chosen to obtain each of these four metals.

Figure 2 shows part of the reactivity series of metals.

Which metal reacts when added to cold water?

A student investigates the reactivity of four different metals.

The student adds an equal‑sized piece of each metal to separate test tubes containing dilute hydrochloric acid.

The student’s observations for zinc and copper are recorded in Figure 3.

Use the information in Figure 2 and in Figure 3 to predict the observations for the reactions of magnesium and of iron with dilute hydrochloric acid.

magnesium

iron

When metals react with acids, hydrogen gas is produced.

Describe the test to show that the gas is hydrogen.

When magnesium reacts with hydrochloric acid, magnesium chloride and hydrogen are formed.

Complete the balanced equation for the reaction.

Mg +_........ HCl MgCl₂ +_........

An excess of magnesium is added to some dilute hydrochloric acid of pH 2. The mass of hydrogen gas produced is measured.

The experiment is repeated with excess magnesium but with the same volume of dilute hydrochloric acid of pH 1.

State how many times greater the concentration of hydrogen ions is in the acid of pH 1 than in the acid of pH 2.

With the acid of pH 2, the mass of hydrogen gas produced when the reaction is complete is 0.005 g.

Predict the mass of hydrogen gas produced in the reaction with acid of pH 1.

mass =_........ g

The method used to extract a metal from its ore depends on the position of the metal in the reactivity series.

Aluminium is extracted from its ore by electrolysis.

Explain why this method is used to extract aluminium from its ore.

One step in the extraction of titanium metal involves the displacement reaction between titanium chloride, TiCl₄, and magnesium.

This equation can be simplified as

Explain why this displacement reaction can be described as a redox reaction.

The formula of the sulfate ion is SO²⁻₄.

Which of the following is the formula of titanium sulfate containing the Ti⁴⁺ ion?

Phytoextraction is an alternative biological method that can be used to extract metals from very low-grade ores.

Give one disadvantage of phytoextraction as a method of extraction of metals.

Copper is low down in the reactivity series and can be obtained from copper oxide.

Devise a simple method to obtain a sample of copper from copper oxide in the laboratory.

A student carried out an investigation to determine the order of reactivity of four metals, W, X, Y and Z. A piece of metal W was added to a test tube containing excess dilute hydrochloric acid. This was repeated with the other three metals, X, Y and Z. In each case, the size of each piece of metal was the same. The student recorded observations on each reaction for three minutes.

The observations obtained are shown in Figure 6.

Use the information in Figure 6 to place the metals in order of reactivity from the least reactive to the most reactive.

The experiment was repeated using an excess of dilute sulfuric acid in place of the dilute hydrochloric acid.

metal + sulfuric acid metal sulfate + hydrogen

When metal Y reacts with dilute sulfuric acid, bubbles form quickly at first and then the reaction stops. Most of the solid metal remains.

Explain why the reaction between metal Y and excess dilute sulfuric acid stopped even though there was solid metal Y left.

The reactions between metals and dilute ethanoic acid are slower than reactions between metals and dilute hydrochloric acid. This is because ethanoic acid is a weak acid.

Explain the meaning of the term weak acid.

The formula of aluminium sulfate is Al₂(SO₄)₃.

Calculate the total number of atoms that combine to form 5.13 g of aluminium sulfate.

(relative atomic masses: O = 16.0, A l = 27.0, S = 32.0 Avogadro number = 6.0210²³)

number of atoms =_........

Iron is more reactive than lead. Iron reacts with lead nitrate solution to form solid lead. Two possible balanced equations for the reaction are

Equation 1 Fe + Pb(NO₃)₂ Fe(NO₃)₂ + Pb

Equation 2 2Fe + 3Pb(NO₃)₂ 2Fe(NO₃)₃ + 3Pb

In one experiment, it was found that 4.48 g of iron reacted with excess lead nitrate solution to form 24.84 g of lead.

Carry out a calculation, using the information above, to show which equation represents the reaction taking place.

(relative atomic masses: Fe = 56.0, Pb = 207)

When chromium reacts with oxygen, chromium oxide is formed.

Write the word equation for this reaction.

What type of reaction occurs when chromium reacts with oxygen?

Calculate the relative formula mass of chromium oxide, Cr₂O₃.

(relative atomic masses: O = 16, Cr = 52)

relative formula mass =_........

Three different metals are added to separate test tubes of acid.

The observations are shown in Figure 2.

Place the metals in order of reactivity from most to least reactive.

most reactive_........

Hydrogen is given off when magnesium reacts with acid. The hydrogen is tested by collecting the gas in a test tube and igniting it.

What is the safest way to ignite the gas?

State the observation made in this test that shows that the gas is hydrogen.

Iron is extracted by heating iron oxide with carbon. Electrolysis of molten iron oxide is not used to extract iron.

State why iron can be extracted by heating iron oxide with carbon.

State why electrolysis is not used to extract iron.

The order of reactivity of copper, magnesium and zinc can be determined by the displacement reactions between these metals and solutions of their salts.

You are provided with

• samples of the three metals

• solutions of copper sulfate, magnesium sulfate and zinc sulfate.

Describe the experiments that can be done to determine the order of reactivity of these metals by displacement reactions.

Metals can be extracted from ores found in the Earth’s crust.

Explain why aluminium cannot be extracted from its ore by heating with carbon but can be extracted by electrolysis.

Titanium is extracted from its ore in several stages.

In the first stage, titanium chloride is formed as a gas.

The gas is cooled to form liquid titanium chloride containing dissolved impurities.

Suggest how pure titanium chloride could be separated from the impurities.

In another stage, the pure titanium chloride, TiCl₄, is reacted with 500 moles of magnesium, an excess.

Calculate the number of moles in 45 000 grams of titanium chloride.

(relative atomic masses: C l = 35.5, Ti = 48.0)

number of moles titanium chloride =_........

Show that the 500 moles of magnesium added is an excess.

After this reaction, there is a mixture of the solids magnesium, titanium and magnesium chloride.

Titanium does not react with dilute hydrochloric acid.

Suggest a simple method to separate titanium from the mixture.

Calcium has an atomic number of 20. A calcium atom has a mass number of 40.

Which row of the table shows the number of protons and number of neutrons in this atom of calcium?

Figure 6 shows the arrangement of electrons in an atom of calcium.

Explain, using the information in Figure 6, in which period of the periodic table calcium can be found.

Calcium and potassium react with water in similar ways.

One similarity in the reactions is that hydrogen gas is produced.

State one other similarity in the products of the reactions of calcium and potassium with water.

Potassium is higher in the reactivity series than calcium and reacts more vigorously with water than calcium reacts with water.

State why potassium is higher in the reactivity series and reacts more vigorously with water than calcium.

*(c) Calcium chloride can be prepared by the reaction of calcium with chlorine gas.

Figure 7 shows some properties of calcium, chlorine and calcium chloride.

Explain, in terms of bonding and structure, why the properties of the product, calcium chloride, are different from the properties of the reactants, calcium and chlorine.

(a) The reactivity of copper, magnesium and zinc was investigated. Each metal was placed separately in dilute hydrochloric acid. The amount of effervescence was observed.

The same mass of metal was used in each experiment. Which piece of apparatus should be used to find the mass of metal used?

State two variables, apart from the mass of the metals, that should be controlled in this investigation.

Magnesium produces the most vigorous effervescence. Copper does not produce any effervescence.

Give the reason why copper does not produce any effervescence.

The magnesium reacts with dilute hydrochloric acid to form magnesium chloride solution and hydrogen gas.

The equation for the reaction is

Mg(s) + 2HCl(aq) MgCl₂(_........ ) + H₂(_........ )

Fill in the missing state symbols in the spaces provided.

Potassium carbonate reacts with dilute sulfuric acid to form potassium sulfate.

Potassium sulfate contains potassium ions, K⁺, and sulfate ions, SO₄²⁻.

Write the formula of potassium sulfate.

Equal volumes of a solution of potassium carbonate were reacted separately with an excess of dilute sulfuric acid solution. Pure dry samples of potassium sulfate were obtained from the resulting solutions.

The experiment was repeated three times using the same conditions.

The masses of potassium sulfate obtained were

experiment 1 = 5.22 g experiment 2 = 5.24 g experiment 3 = 5.21 g

Calculate the mean mass of potassium sulfate obtained, giving your answer to two decimal places.

mean mass of potassium sulfate =_........ g

Pieces of zinc react with copper sulfate solution. Zinc sulfate solution is colourless.

Describe what you would see when an excess of zinc is added to copper sulfate solution and the mixture left until the reaction is complete.

This reaction is described as a redox reaction.

Explain, in terms of electrons, which particles have been oxidised and which particles have been reduced in this reaction.

The copper sulfate solution used has a concentration of 15.95 g dm⁻³.

Calculate the number of moles of copper sulfate, CuSO₄, in 50.00 cm³ of this solution. (relative atomic masses: O = 16, S = 32, Cu = 63.5)

number of moles of copper sulfate =_........ mol

In another experiment, 0.043 mol of copper sulfate, CuSO₄, is used.

Calculate, to one decimal place, the minimum mass of zinc that must be added to react with all the copper sulfate. (relative atomic mass: Zn = 65)

mass =_........ g

(a) A student placed a piece of metal P in a test tube containing excess dilute sulfuric acid. The student repeated this with three other metals, Q, R and S. All the pieces of all four metals were the same size.

The student recorded the observations until each metal had reacted with the acid for two minutes. The observations are shown in Figure 6.

Use this information to put the four metals in order of reactivity from the least reactive to the most reactive.

least reactive
most reactive

Acid solutions contain hydrogen ions.

Aluminium reacts with dilute hydrochloric acid to form a solution containing aluminium ions, Al³⁺.

Complete the balanced ionic equation for this reaction.

_........ +_........ H⁺ _........ Al³⁺ +_........

The hydrogen ion concentration in a solution is decreased by a factor of 10.

State how the pH of this solution changes.

Calculate the mass, in g, of a hydrogen atom, using the data below. (relative atomic mass: H = 1.00; Avogadro constant = 6.02 × 10²³)

mass of hydrogen atom =_........ g