chem paper 2 2023

what is limewater an aqeous solution of

calcium hydroxide

whats on compound to a product of the reaction of the compound with ehtanoic acid

sodium carbonate

carbon dioxide

which isnturment method can be used ot show the prescence of potassium ions in the medecine

flame emmision spectroscopy

whats a greenhouse gas nitrogen or water vapour

water vapour

explain why the increase in world population may have caused the increase in the concentration of methane in the atmosphere

more wast produced

which produces more methane on decomposition

describe two potential effects of the increase in the mean temperatrue of the atmosphere at the Earth’s surface

melting ice

rising sea levels

loss of habitat

The mean temperature of the atmosphere at the Earth’s surface has increased.

Most scientists think that this has been caused by an increase in the concentration of

greenhouse gases in the atmosphere.

Give one reason why some scientists do not accept this theory.

the earth goes through cycles of temp change

Explain why the Rf values for the red dye are different using the two types of chromatography paper.

Rf value is smaller for paper A

because red dye is more attracted to paper A than B

so red dye

what other changes to the investigation could result in a different Rf value for the red dye

use different solvent

whats the solvent

the water

whats the solute

the dye

Give the general name for the four different monomers which make up the structure shown

nucleotides

When 4.68 g of hydrated copper sulfate changes into anhydrous copper sulfate:

• 2.99 g of anhydrous copper sulfate is produced

• 1.47 kJ of energy is taken in from the surroundings.

The equation for the reversible reaction is:

hydrated copper sulfate ⇌ anhydrous copper sulfate + water

Calculate the maximum mass of water that can be produced from 11.7g of hydrated copper sulfate.

4.68 - 2.99 = 1.699

11.7 / 4.68 × 1.69 = 4.23g

When 4.68 g of hydrated copper sulfate changes into anhydrous copper sulfate:

• 2.99 g of anhydrous copper sulfate is produced

• 1.47 kJ of energy is taken in from the surroundings.

When 4.68 g of hydrated copper sulfate changes into anhydrous copper sulfate:

• 2.99 g of anhydrous copper sulfate is produced

• 1.47 kJ of energy is taken in from the surroundings.

15 / 2.99 × 1.47 = 7.37

What is the colour of the mixture when a new equilibrium position is reached?

• darker shade of brown

• same shade of brown

• mixture is a lighter shade of brown

lighter shade

2 HI(g) ⇌ H2(g) + I2(g)

Explain the effect of increasing the pressure on the equilibrium position of this reaction.

no effect on equilibrium

because there’s an equal number of gas molecules on both

The reaction mixture is green when both copper compounds are present in a solution at equilibrium.

How can the equilibrium position be shifted to make the reaction mixture more yellow?

• add more hydrochloric acid

• add more water

• leave the reaction mixture for 30 minutes

add more hydrochloric acid

A scientist analysed the percentages of nitrogen, phosphorus and potassium in a soil.

The percentages of nitrogen and of potassium in the soil were lower than the percentages needed for high agricultural productivity.

There was sufficient phosphorus in the soil for high agricultural productivity.

Evaluate the use of the compounds in Table 4 to improve the agricultural productivity of this soil.

how is potassium chloride obtained form the eath

mining

Name one other compound that could be used instead of potassium chloride (compound A) to give a similar improvement in agricultural productivity.

potassium sulfate

Nitric acid is needed to produce ammonium nitrate (compound B).

Name a compound needed to produce nitric acid.

ammonia

Phosphate rock contains phosphorus compounds.

Plants absorb phosphorus from compounds dissolved in rainwater.

Suggest why phosphate rock cannot be used directly as a fertiliser.

insoluble in water

Phosphate rock can be treated with different acids to produce salts useful as fertilisers.

Name the salts which are produced by treating phosphate rock with:

• sulfuric acid

• phosphoric acid.

sulfuric acid - calcium sulfate

phosphoric acid - calcium phosphate