Analysis, Conclusions and Evaluation
237 questions· page 1 of 24
Argentan is an alloy containing only zinc, nickel and copper.
Zinc and nickel both react with dilute hydrochloric acid. Copper does not react with dilute hydrochloric acid.
Plan an investigation to find the percentage by mass of copper in a powdered sample of argentan.
Your plan must include the use of common laboratory apparatus, argentan and dilute hydrochloric acid. 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 by mass of copper in the sample.
You may draw a diagram to help answer the question.
Muntz metal is an alloy that contains zinc and copper.
Zinc reacts with dilute sulfuric acid. Copper does not react with dilute sulfuric acid.
Plan an investigation to find the percentage by mass of zinc in a powdered sample of Muntz metal which contains only zinc and copper.
Your plan must include the use of common laboratory apparatus, Muntz metal and dilute sulfuric acid. 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 by mass of zinc in the sample of Muntz metal.
You may draw a diagram to help answer the question.
Baking powder is used to make cakes rise. When water is added to baking powder, carbon dioxide gas is released.
The longer the baking powder is stored, the less carbon dioxide it releases when water is added.
Plan an investigation to show which of two different samples of baking powder has been stored for longer.
Your plan should include the use of common laboratory apparatus, the two samples of baking powder and water. No other chemicals should be used.
Your plan should include:
- the apparatus needed
- the method to use
- the measurements to take
- the variables to control
- how to use the results to determine which sample has been stored for longer.
You may draw a diagram to help you answer the question.
A student is provided with two bottles labelled A and B and a supply of water.
One of the bottles contains of solid potassium chloride, .
The other bottle contains of solid calcium chloride, .
When potassium chloride dissolves in water the change is endothermic.
When calcium chloride dissolves in water the change is exothermic.
Plan experiments, based on dissolving the solids in water, to decide:
- which compound is in each bottle
- which compound produces the greatest heat change per gram of solid.
Your plan may use any of the apparatus normally found in a chemistry laboratory but no other chemicals.
Your plan must state all the measurements you need to make.
Your plan must use the same experimental procedure for each solid.
The temperature rise with each mass of magnesium is less than expected. Give one reason for this.
______
State two changes that can be made to the apparatus so that the temperature rise for each mass of magnesium is closer to the expected value for each mass.
- ______
- ______
The diagrams show parts of the thermometer stem giving the highest temperature recorded using different masses of magnesium.
Use the thermometer readings to complete the following table.
| mass of magnesium / | initial temperature of hydrochloric acid / | highest temperature of hydrochloric acid / | temperature rise / |
|---|---|---|---|
| 0.10 | 20.0 | 22.6 | 2.6 |
| 0.20 | 20.0 | ||
| 0.30 | 20.0 | ||
| 0.40 | 20.0 | ||
| 0.50 | 20.0 | ||
| 0.60 | 20.0 | 32.4 | 12.4 |
| 0.70 | 20.0 | 32.4 | 12.4 |
Plot the temperature rise against the mass of magnesium on the grid.
Draw a straight line through the first four points.
Draw another straight line through the last three points. Extend both straight lines so that they cross.
What is the minimum mass of magnesium that reacts with all of the hydrochloric acid?
______
Use your answer to (e) (iv) to calculate the number of moles of magnesium that reacts with of dilute hydrochloric acid.
[: , 24]
______
Magnesium reacts with dilute hydrochloric acid.
Calculate the concentration, in , of the hydrochloric acid.
______
What volume of carbon dioxide gas, measured at room temperature and pressure, is produced when of ethanol is burned in an excess of oxygen?
[: H, 1; C, 12; O, 16]
[1 mole of a gas occupies a volume of at room temperature and pressure.]
| (a) | |
| (b) | |
| (c) | |
| (d) |
In questions 3 to 5 inclusive, place a tick (✓) in the box against the correct answer.
A student finds that a compound contains 4.8 g of carbon, 0.8 g of hydrogen and 6.4 g of oxygen.
[: C, 12; H, 1; O, 16]
What is the empirical formula of the compound?
(a) [ ]
(b) [ ]
(c) [ ]
(d) [ ]
In questions 3 to 6 inclusive, place a tick (✓) in the box against the correct answer.
A student burns 4.8 g of an element X in excess oxygen. The mass of the oxide produced is 8.0 g.
What is the empirical formula of the oxide of X?
[: X, 24; O, 16]
(a) XO
(b) X₂O
(c) X₂O₂
(d) X₃O₅
A student adds excess zinc to hydrochloric acid and measures the volume of hydrogen gas given off at regular time intervals. This is experiment 1.
The student makes a change to one of the conditions and then repeats the experiment. This is experiment 2.
The volume of hydrochloric acid is the same in both experiments.
Graphs for both experiments 1 and 2 are shown.
What is the different condition used in experiment 2?
(a) A catalyst is added.
(b) A higher temperature is used.
(c) A greater mass of zinc is used.
(d) A higher concentration of hydrochloric acid is used.
A student passes air backwards and forwards over heated copper using the apparatus shown. The original volume of air in the apparatus is .
The experiment continues until the volume of gas stops changing. Some unreacted copper remains.
What is the final volume of gas in the apparatus?
[All volumes are measured at room temperature and pressure.]
(a)
(b)
(c)
(d)