Chemistry Hw Help (2 Viewers)

[RachelGreen]

Hello BOS ppl, can anyone help me with these questions. I have really dodgy answers and don't know whether it's satisfactory.
1. Give two reasons why care needs to be taken when collecting water samples for testing. (2)
- Take samples of water not near the bank of the water body, as this may not be a source of water supply
- If a composite sample is to be submitted for analysis, pour equal portions of freshly collected
samples into a suitable container.

What do you think about that answer?

2. Outline ways to improve accuracy and reliability of this experiment: The analysis of water quality? (2)
I know for reliability, I can repeat tests until I achieve consistent results. BUt I'm stuck on accuracy

3. Evaluate the quality of tap water and lake water? [2]
What am I suppose to be talking about here? I know the one mark is for my judgement. What's the other mark for, and how would I go about answering?

4. Identify one way a river could become turbid, and outline the impact of increased turbidity on aquatic flora and fauna. [3]
A thing I don't understand is, is the river a catchment area? If so, could the river/catchment area become more turbid after a flood or something? And how does it affect the plants and stuff?

 

[RachelGreen]

Thanks in advance. ONe more question. Is this really trial questions?

 

[buckskinbrumby]

1. - make sure theres no air bubbles (especially if doing BOD/DO testing) as it will change the results (the air will diffuse into the water and give an inaccurate reading)
- make sure that no silt/contamination gets in (stand downstream, don't upset the riverbed etc.)

2. use probes and manual tests, 2 or more decimal places

3. tap water has been treated to remove contaminants and harmful substances, whereas lake water is just water and whatever has flowed/gone into it (could possibly mention water purification process)

4. rivers can be catchment areas, however whether it's a catchment or not, it will get turbid during a flood. The turbidity lets less light through for the plants to perform photosynthesis, and so there is less of that happening. Turbidity can also mean that some animals might find it harder to find food due to more particles within the water etc.

Could be a trials question, haven't done them yet so not sure haha. Hope that helped

 

[RachelGreen]

Oh thank you! Also, how do you convert from g to mg? Do you times 1000?

 

[InteGrand]

Oh thank you! Also, how do you convert from g to mg? Do you times 1000?

Yes, 1 g = 1000 mg.