### chemistry worksheet stuck on this question

Calculate the number of moles and the mass of MgCO3 in the sample, and hence deduce the percentage by mass of MgCO3 in the sample.

0

### chemistry

help can someone check this:

1) 25.0cm³ of NaOH is neutralized by 150 cm³ of HCl acid of concentration of 0.25 mol dm⁻³. Find the concentration of the sodium hydroxide solution (NaOH).

Working out:
NaOH + HCl
1:1

NaOH = concentration? Volume=25.ocm³ mole?

HCl = concentration=0.25 Volume=150cm³ mole?

N=C × Vcm³/1000 = 150÷1000=0.15

Mol = C × V =0.15×0.25=0.375
As the relationship between NaOH & HCl is 1:1 the number of moles would be the same.
Concentration = M÷ V
25÷1000= 0.025
0.0375÷0.025=1.5

0

### Re: A Level biology help

How does blood move through the vessels ( arteries, veins & capillaries) ?

0

### Mind Maps

Mind maps help to cram all the topic info onto one page, can be colorful and include funny pictures to jog your memory, and can be really fun to do. Also try doing a "perfect" mind map and then getting a blank piece of paper and copy it out without looking at it and see how much u remember. Anything u don't remember, try to remember next time. Hope that helped! :) P.S. this helped me to get a* in my unit 1 chem exam

0

### Revision tips

Creating good conditions to study in can help you make the most of the time you spend revising. Here are some suggestions:

Find a quiet place to study and make sure you are sitting comfortably
Make sure your desk is well lit
Keep background noise to a minimum
Avoid studying in an area where there will be distractions (like television!)
Have everything you need to do your revision to hand before you start

There is no ‘right way’ to revise, as long as the method you choose enables you to gain a solid grasp of key facts and consolidate your knowledge. Some students are happy to read their classroom notes from start to finish, others prefer to simplify the information as much as possible, turning everything into skeleton notes, diagrams or mnemonics. In practice, most students find that mixing techniques suits the varied nature of the subjects being revised, and provides essential variety when studying.

Turn your notes into revision tools;
write ideas and facts on to cards to use as ‘prompts’
create memory aids such as diagrams or mnemonics (e.g. initial letters to make a word you need to remember or SMART objectives: Specific; Measurable; Achievable; Realistic; Targets). These will help you remember key facts
write key facts/notes out and display these around the house where you will see them
for more tips go on http://www.cambridgestudents.org.uk/examtime/revisiontips/index_html#1
one more thing is that i would meditate regularly helps your memory and keeps you calm before going into the exam moreover have breaks in between please do not stress yourself as the information wont sink in trust me :-))))))

0

### Post it notes

For things I cant remember i plaster post it notes everywhere so I eventually remember it !

0

### Revsie with friends

I find revising with friends helps me especially when we test each other after every new topic that we've learnt !

0
When do you normally start revising for exams?