Chem Paper 2

Question 1

Explain why water vapour and not liquid water is produced when diesel burns

Answer 1

Diesel burns at a high temperature which is above the boiling point of water

Question 2

Sulfur is a common impurity in diesel. Explain why this causes an environmental problem

Answer 2

Sulfur dioxide is produced when diesel burns which can cause acid rain which erodes buildings and causes respiratory problems

Question 3

Chromatography

Answer 3

Draw a pencil line near the bottom of the paper, put a small dot of black ink on the pencil line in a beaker as a small amount of solvent and place the paper in the solvent making sure that the ink dot is above the amount of solvent support there paper in that position and put a load on the beaker, leave to run and then let it dry. Calculate the RF value using: distance travelled by substance/distance travelled by solvent

Question 4

Describe how crude oil is separated into fractions

Answer 4

Crude oil is heated to vaporise the hydrocarbons, as you go up the column get cooler, the hydrocarbons condenser at different heights because they have different boiling points

Question 5

Explain why alkanes are cracked

Answer 5

To make smaller hydrocarbon molecules because they are high in demand/more useful

Question 6

Test for hydrogen

Answer 6

Lit splint
If it makes a squeaky pop sound hydrogen is present

Question 7

Chlorine test

Answer 7

Damp litmus paper
If the paper bleaches chlorine is present

Question 8

Explain why portable water contains dissolved solids after filtering

Answer 8

The dissolved solid particles pass through the filter paper because they are very small

Question 9

Explain how greenhouse gases cause global warming

Answer 9

Greenhouse gases allow short wavelength radiation to enter the atmosphere, which are absorbed by the earth and re-emitted as long wavelength radiation which is absorbed by greenhouse gases in the atmosphere this increases the temperature causing globally warming

Question 10

Explain how planting trees reduces global warming

Answer 10

Trees use carbon dioxide for photosynthesis, carbon dioxide causes global warming

Question 11

Oxygen test

Answer 11

Glowing splint
If splint relights oxygen is present

Question 12

Using 10cm³ of hydrogen peroxide solution gives less accurate results than using 20cm³ of hydrogen peroxide solutionf the same concentration. Explain why

Answer 12

Smaller volume of gas produced per unit time so reading error is a larger percentage of the total volume

Question 13

Suggest one possible systematic error in this investigation

Answer 13

Measuring vessel wrongly calibrated, balance wrongly calibrated, timer slow/fast

Question 14

The rate of reaction is not dependent on the volume of hydrogen peroxide solution. Explain why.

Answer 14

Same number of particles per unit volume so same frequency of collisions