To Determine The Total Suspended Solifd And Dissolved Solids

Question 1

Describe how a student could determine by filtration the total suspended solids in the water

Answer 1

Filter known volume of water through weighed filter paper, dry the filter paper and reweigh. Find the increase of mass and this is the mass of the suspended solids. Express the mass in mg/l

Question 2

Describe how a student could determine the total dissolved solids in a sample of filtered seawater

Answer 2

Evaporate known volume of filtered water in weighed dish. Allow to cool and reweigh to find increase in mass this is the mass of dissolved solids. Express the mass in mg/l

Question 3

Suggest a possible cause of high levels of total suspended solids

Answer 3

Heavy rainfall results in large amounts of suspended solids (from soil, plants) being washed into rivers and lakes. Water taken from these rivers and lakes would have high levels of total suspended solids

Question 4

What undesirable effects could result from high levels of total suspended solids

Answer 4

Cause water to be cloudy or brown (due to soil)

Question 5

In the experiment to determine the concentration of dissolved solids, why must filtered water be used?

Answer 5

Filtered water must be used in order to ensure that any suspended solids have been removed from the water. Otherwise, an inaccurate reading would be obtained since the suspended solids would be weighed with the dissolved solids when the water is evaporated.

Question 6

Suggest a possible reason for high levels of total dissolved solids

Answer 6

Since water is an excellent solvent, it always contains some levels of dissolved solids. High levels of total dissolved solids may be caused by the water flowing through areas that contain large amounts of substances which dissolve in water eg, calcium hydrogencarbonate and calcium choride

Question 7

Suggest two reasons for a relatively high PH value in a water sample

Answer 7

1) Water may come from limestone region and this can cause water to be very alkaline
2) Due to fact that water authority may have softened the water by adding a substance like sodium carbonate at the treatment stage. Since sodium carbonate is a base, this will raise the PH value

Question 8

State a precaution in this experiment

Answer 8

Removing the tube before turning the tap off to prevent suckback

Question 9

How to do you measure the PH of a sample of water?

Answer 9

Using a PH meter
Calibrate meter in buffer solution and then wash with deionised water and place electrode in test sample
Read PH value

Question 10

To measure the PH of a sample of water, what can be used instead of a PH meter

Answer 10

Universal Indicator Paper

Question 11

CALCULATIONS (Check sheet)

Answer 11

Find g/l (divide by volume and multiply by 1000) and then get it in ppm

Question 12

Describe how suspended solids are removed in water treatment

Answer 12

Settlement - allow solids to settle
Flocculation - aluminium sulfate (flocculating agent) is added which joins particles together
Decanting the water
Filtration - sand filters remove any remaining suspended solids

Question 13

How does high levels of suspended solids impact aquatic life?

Answer 13

It reduces light penetration in surface waters and may interfere with plant and aquatic life

Question 14

What are the undesirable effects which could result from high levels of total suspended solids

Answer 14

Eutrophication

Question 15

How is the mass of the supsended solids actually determined?

Answer 15

By the increase in mass of filter paper

Question 16

Diagram of suspended solids

Answer 16

Buchner funnel and filter paper, Buchner flask with filtrate, and vaccuum pump (122 of revision day book)

Question 17

What is the term given to water that may have high levels of dissolved solids

Answer 17

Indication that water is Saline

Question 18

Suggest a reason for a relatively low PH reading

Answer 18

Water flowing through bogs which are acidic or peaty

Organic material decomposes to form acidic substances

Question 19

What is the most common PH range in fresh waters?

Answer 19

6-8

Question 20

Describe how the concentration of suspended solids could have been measured

Answer 20

known volume of water sample through filter paper of known mass
dry filter paper / place in oven (on radiator, etc)
find new mass of filter paper and residue

Question 21

Calculate the mass in grams of dissolved solids in 250cm^3 of sample with 1400ppm

Answer 21

1400 mg/l / 1000 = 1.4 g/l / 4 = .35g/250

Question 22

When a water sample was boiled, filtered and re-analysed for hardness, the result was loywer than the first, suggest a reason why

Answer 22

Temporary hardness was removed