Types of chemical reactionIB MYP Sciences: Subtopic test

1. 1
   In a school laboratory in Cairo, a student heats a spatula of green copper carbonate powder in a test tube using a Bunsen burner. After a few minutes the powder has turned black. A gas is given off that turns limewater cloudy. When the student stops heating, the reaction stops.

   (a)

   Which type of reaction takes place when copper carbonate is heated?

   [1 mark]

   • ASynthesis
   • BNeutralisation
   • CDisplacement
   • DDecomposition

   (b)

   The student has to keep heating for the reaction to continue. What does this show?

   [1 mark]

   • AThe reaction is exothermic, because it gives out heat to the surroundings
   • BThe reaction is endothermic, because it takes in energy from the surroundings
   • CThe reaction is combustion, because a Bunsen burner is used
   • DThe reaction is precipitation, because a solid forms

   (c)

   Explain, using the observations, why this is a chemical change.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A student in Johannesburg places a clean iron nail in a beaker of blue copper sulfate solution. After 20 minutes the nail is coated with a pink-brown solid and the blue colour of the solution has become paler.

   (a)

   What type of reaction takes place between the iron nail and copper sulfate solution?

   [1 mark]

   • ADisplacement
   • BNeutralisation
   • CDecomposition
   • DCombustion

   (b)

   Which statement explains the observations?

   [1 mark]

   • ACopper is more reactive than iron, so copper displaces the iron
   • BThe iron neutralises the copper sulfate
   • CIron is more reactive than copper, so it takes the place of copper in the solution and copper metal coats the nail
   • DThe iron nail decomposes into copper

   (c)

   Write a word equation for the reaction.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A student in Mexico City mixes 25 cm³ of dilute hydrochloric acid with 25 cm³ of dilute sodium hydroxide solution in a polystyrene cup. Both solutions start at 21.0 °C. After stirring, the highest temperature reached is 27.5 °C, and universal indicator added to the mixture turns green.

   (a)

   Identify the type of reaction, name the two products and explain what the temperature rise shows.

   [3 marks]

   (b)

   The student plans a second investigation to find how the concentration of the acid affects the temperature rise. Identify the independent variable and the dependent variable, and name two variables she must keep the same.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   Iron is extracted from iron oxide ore in blast furnaces in countries such as India, by heating the ore with carbon in the form of coke. The iron is used to make steel for buildings, bridges and railways. The process needs very high temperatures and burns large amounts of carbon.

   (a)

   Explain, using the ideas of oxidation and reduction, what happens in this reaction. Include a word equation and a balanced symbol equation, and refer to the reactivity of carbon and iron.

   [6 marks]

   (b)

   Discuss and evaluate the use of blast furnaces to produce iron and steel.

   [6 marks]

   Total for question 4: 12 marks

End of questions