Help with prac!! Analysis of beach sand (1 Viewer)

[rosegazing]

My entire chemistry (year 11) class is kinda stuck on a prac investigation we have to do. We know roughly what we need to do but we are worried that we won't have enough time (around 50 minutes)

We are given a sample of sand (containing quartz, calcium carbonate and salt, possibly other impurities) and have to complete a gravimetric analysis. We need to separate the components and then find their percentages.

What we have figured out is:
Firstly we wash away any salt and impurities using water and filter paper.
Secondly we add hydrochloric acid to the filtrate to separate the calcium carbonate from the quartz. We are left with quartz, water and CaCl₂ (which will dissolve into the water) (CO₂ will leave as bubbles I'm assuming).
Lastly we filter the quartz from the water.

We need to weigh the mixture before we start for the total weight. We also need the weight of the impurities, the quartz and the calcium carbonate. So we need to weigh either the impurities (dry) or the quartz/calcium carbonate mixture (dry) and do some maths to find out whatever we didn't weigh. We also would need to weigh the quartz at the end. The most time consuming part will most likely be the drying process.

If you have any ideas on fast ways to dry the substances and which substances we should actually dry and when to weigh them, that would be great.

And if there is something we should be doing totally differently please let me know!

Thankyou!!!

 

[ahri]

I don't think there are many faster ways other than evaporating as much as possible and leaving it in the sun or in a dehydrator, not sure if your school has it though. But yeah, in 50 minutes, I really doubt you would have a enough time to do that so it's just something you could put in a discussion as a source of potential error.

 

[jazz519]

I don't think you can change the method too much as the equipment you have in a school setting is limited.

One of the things you could talk about in the discussion could be about the sample not being dried fully so the mass that was weighed would have water in it, increasing its true value.

You should also mention improvements to the method, so for that above problem what you can do is use a vacuum pump to remove the water faster (common practice in a uni lab setting)

Just one piece of advice a lot of students when they go into these practical exams think that the most important part of the whole assessment is doing practical, and therefore they don't prepare as much for the discussion and other questions they can ask you on the practical

So make sure you have points of discussion for accuracy, validity and reliability prior to the experiment

You should also know any relevant chemical equations that occurred during your experiment these are things that you can talk about in a discussion

If you have any other specific questions let me know

 

[rosegazing]

I don't think you can change the method too much as the equipment you have in a school setting is limited.

One of the things you could talk about in the discussion could be about the sample not being dried fully so the mass that was weighed would have water in it, increasing its true value.

You should also mention improvements to the method, so for that above problem what you can do is use a vacuum pump to remove the water faster (common practice in a uni lab setting)

Just one piece of advice a lot of students when they go into these practical exams think that the most important part of the whole assessment is doing practical, and therefore they don't prepare as much for the discussion and other questions they can ask you on the practical

So make sure you have points of discussion for accuracy, validity and reliability prior to the experiment

You should also know any relevant chemical equations that occurred during your experiment these are things that you can talk about in a discussion

If you have any other specific questions let me know

I don't think there are many faster ways other than evaporating as much as possible and leaving it in the sun or in a dehydrator, not sure if your school has it though. But yeah, in 50 minutes, I really doubt you would have a enough time to do that so it's just something you could put in a discussion as a source of potential error.

Thanks guys! We finally got a chance to speak with our teacher today and she said that we can put them in an incubator and weigh them the next lesson. Solves that problem!
I have already been telling everyone that if something doesn't go the way you hope that you can put it in the discussion, hopefully they'll stop freaking out now more people have said it.