Experimental Contexts
401 questions· page 1 of 41
Q is a mixture of solid magnesium oxide and solid barium sulfate.
Magnesium oxide is insoluble in water. It reacts with dilute hydrochloric acid to make a solution of magnesium chloride.
Barium sulfate is insoluble in water and does not react with dilute hydrochloric acid.
Plan an investigation to obtain pure magnesium chloride crystals and pure barium sulfate solid from Q.
Your plan should describe the use of common laboratory apparatus, dilute hydrochloric acid and Q. No other chemicals should be used.
Your plan should include:
- the apparatus needed
- the preparation of magnesium chloride solution
- the method to obtain pure magnesium chloride crystals
- the method to obtain pure barium sulfate solid
- how to test that the barium sulfate is pure.
You may draw a diagram to help answer the question.
The student does not make an important measurement.
State the measurement that the student needs to make.
______
The student's results are shown in Table 1.1.
Table 1.1
| temperature / | mass of potassium nitrate dissolved in of water / |
|---|---|
| 15 | 26.4 |
| room temperature | 31.7 |
| 35 | 54.9 |
| 55 | |
| 75 | 152.4 |
| 95 | 225.3 |
Estimate the mass of potassium nitrate dissolved in of water at .
mass = ______
The student observes that when the solution made at is left at room temperature a solid appears in the beaker.
Explain why.
______
Explain why the method the student uses gives a higher value for the solubility than the true value.
______
The student observes a blue-green colour in the flame.
Identify the cation present in A.
______
Describe the observations the student makes. Describe the chemical test and the positive result used to identify the gas formed.
observations ______
test ______
result ______
Explain how the student uses aqueous ammonia to confirm the metal ion present in C.
Include the observations you expect.
______
The student does tests on B. The results are shown in Table 3.1.
Table 3.1
| test | observation |
|---|---|
| adds dilute nitric acid and aqueous barium nitrate | colourless solution formed |
| adds dilute nitric acid and aqueous silver nitrate | cream precipitate formed |
| adds aqueous sodium hydroxide and aluminium foil then warms the mixture | colourless solution formed |
Identify the anion in B.
______
Q is a mixture of solid copper(II) carbonate and solid lead sulfate.
Lead sulfate is insoluble in water and does not react with dilute sulfuric acid.
Copper(II) carbonate is insoluble in water. It reacts with dilute sulfuric acid to form copper(II) sulfate solution.
Plan an investigation to obtain pure copper(II) sulfate crystals and pure lead sulfate solid from Q.
Your plan should describe the use of common laboratory apparatus, dilute sulfuric acid and Q. No other chemicals should be used.
Your plan should include:
- the apparatus needed
- the preparation of copper(II) sulfate solution
- the method to obtain pure copper(II) sulfate crystals
- the method to obtain pure lead sulfate solid
- how to test that the lead sulfate is pure.
You may draw a diagram to help answer the question.
State the name of the piece of apparatus the student uses to safely heat the petroleum in Fig. 1.1.
Explain why this piece of apparatus is suitable.
piece of apparatus ______
explanation ______
Alcohols are used as fuels to heat water.
Plan an experiment to determine which alcohol, methanol or ethanol, releases more thermal energy per gram of alcohol burned.
Your plan should describe the use of an alcohol burner, as shown in Fig. 4.1, to heat water. You should use water, methanol, ethanol and common laboratory apparatus. No other chemicals should be used.
Your plan should include:
- the additional apparatus needed
- the method to use and the measurements to take
- how the measurements are used to determine which alcohol releases more thermal energy per gram burned.
You may draw a diagram to help answer the question.
The reaction between a metal and dilute sulfuric acid is exothermic.
Plan an experiment to determine which metal, magnesium or zinc, releases more thermal energy per gram of metal when reacting with excess dilute sulfuric acid.
You are provided with magnesium powder, zinc powder, dilute sulfuric acid and common laboratory apparatus. No other chemicals should be used.
Your plan should include:
- the apparatus needed
- the method to use and the measurements to take
- how the measurements are used to determine which metal releases more thermal energy per gram.
You may draw a diagram to help answer the question.
Barium carbonate decomposes when heated. The word equation for the reaction is shown.
Plan an experiment to determine the percentage loss in mass when barium carbonate is heated.
Your plan must include the use of common laboratory apparatus and a sample of barium carbonate. No other chemicals should be used.
Your plan must include:
- the apparatus needed
- the method to use and the measurements to take
- procedures to ensure that the percentage determined is as accurate as possible
- how the measurements are used to determine the percentage loss in mass.
You may draw a diagram to help answer the question.
The student leaves a wooden splint with one end dipped into R for ten minutes. The student then places the damp end of the wooden splint into the flame of a Bunsen burner with the air hole open.
The student concludes that R contains sodium ions.
State the observation which allows the student to make this conclusion.
______
Explain why the air hole on the Bunsen burner must be open when doing this flame test.
______
The student adds dilute nitric acid to R.
The student observes effervescence of a colourless gas which turns limewater milky.
State the conclusions from these observations.
______
The student adds aqueous barium nitrate to some of the mixture from (b)(i).
The student concludes that R contains sulfate ions.
State the observation which allows the student to make this conclusion.
______
The student adds aqueous silver nitrate to some of the mixture from (b)(i).
The student observes a colourless solution.
State a conclusion from this observation.
______
The student adds aqueous sodium hydroxide to R and warms the mixture.
Describe a test and observation to show that R does not contain ammonium ions.
test = ______
observation = ______
Solution R is made from a mixture of two different ionic compounds.
Suggest the names of these two compounds.
______
The student tests a different solution, P, and finds it difficult to decide whether the solution contains chloride ions or bromide ions.
The student also has aqueous potassium chloride and aqueous potassium bromide.
Suggest how the student could use the aqueous potassium chloride and aqueous potassium bromide to make it easier to decide whether P contains chloride ions or bromide ions.
______
The student adds dilute hydrochloric acid to another solution and a gas is produced. The gas is passed through limewater.
Describe how the gas can be passed through limewater.
You may draw a labelled diagram to help answer the question.
Copper(II) carbonate reacts with dilute sulfuric acid at room temperature.
The word equation for the reaction is shown.
Plan an experiment to determine the volume of carbon dioxide formed when a known mass of copper(II) carbonate completely reacts with dilute sulfuric acid.
Your plan must include the use of common laboratory apparatus, dilute sulfuric acid and copper(II) carbonate. No other chemicals should be used.
Your plan must include:
- the apparatus needed
- the method to use and the measurements to take
- procedures to ensure that the volume measured is as accurate as possible.
You may draw a diagram to help answer the question.