AQA GCSE Combined Trilogy Chemistry 8464 - Paper 2 - 12th June 2019

I said something about the Rf but I know it's probably wrong!

Original post by Paolo3100

how could you identify uknown dyes

Reply 22

I was stumped by this, I said collect 100cm cubed of pure water, and 100cm cubed of river water. Then measure both their masses using a balance, the difference in mass will be the mass of the dissolved solids within the river water. Is that acceptable for marks?

Original post by inayah133

What did people get for the 4 mark question on the mass of dissolved substances?

Reply 23

I did that and then I put something like measure the mass at the start and end to get the mass of the dissolved substances

Original post by Paolo3100

i guessed you would use simple distillation

Reply 24

Paolo3100

19

Original post by inayah133

I said something about the Rf but I know it's probably wrong!

sorry for that question i wrote about the attraction to paper and solubility

Reply 25

Paolo3100

19

for measuring dissolved substances i wrote about simple distillation

Reply 26

What did everyone get for the rounding to 2 significant figure question? To find the mass

Reply 27

Yes, I put something like that- I said to measure the mass at the start and end to get the mass of the dissolved substances! I also put use distillation to turn it into pure water.

Original post by RedLamp444

I was stumped by this, I said collect 100cm cubed of pure water, and 100cm cubed of river water. Then measure both their masses using a balance, the difference in mass will be the mass of the dissolved solids within the river water. Is that acceptable for marks?

Reply 28

K Russell

12

Hardest Science exam I've ever done

Reply 29

Aren't they the factors that depend on the amount of time molecules spend in each phase- mobile and stationary phase though?

Original post by Paolo3100

sorry for that question i wrote about the attraction to paper and solubility

Reply 30

username4746572

17

Same .

Original post by inayah133

I did that and then I put something like measure the mass at the start and end to get the mass of the dissolved substances

Reply 31

I got 0.03125 but then since you have to round it to 2 s.f, I put 0.03100g

Original post by RedLamp444

What did everyone get for the rounding to 2 significant figure question? To find the mass

Reply 32

I got that but I forgot to divide at the end as I had no idea how to do it- I got 3100g to 2sf but I knew it was wrong as I pressed random buttons on the calculator

Original post by RedLamp444

I got 0.03125 but then since you have to round it to 2 s.f, I put 0.03100g

Reply 33

lucayah

7

what did everyone put for the water test? I put test the pH but i'm wrong I think

Reply 34

leonl888

6

Measure mass of evaporating basin and put water in it then evaporate water and remeasure the mass. If the mass increased then there was dissolved salt

Original post by lucayah

what did everyone put for the water test? I put test the pH but i'm wrong I think

Reply 35

gcseexam19

3

Did anyone get 3100 for the first calculation question to 2 significant figures.

Reply 36

Paolo3100

19

for dissolved solids, i put down to evaporate water leaving solids at the bottom of the flask which should turn into crystals. this should be dried and weighed

Reply 37