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Chemistry

A Level

Proteins are an important part of a healthy diet because they provide essential amino acids. (a) State what is meant by an essential amino acid.

There are 20 amino acids, and they can be classified as essential or non-essential – if they are non-essential they can be synthesised by the human body...

Answered by Darragh C. • Chemistry tutor

3147 Views

The recommended daily allowance of methionine for an adult is 15 mg per kg of body mass. Tuna contains 755 mg of methionine per 100 g portion. Calculate the mass, in grams, of tuna that would provide the RDA of methionine for a 60 kg adult.

15mg per kilo recommended dose 15x60 = 900mg recommended dose for a 60kg adult There is 755mg per 100g portion of tuna So 900/755 = 1.19 times the amount in 100g of tuna is the recommended dose 1.19 x 100...

Answered by Darragh C. • Chemistry tutor

4922 Views

Why at room temperature is H2O a liquid, but H2S is a gas?

This question is basically just asking you why water has a higher boiling point that H₂S. So you need to ask yourself what is the factor which means water has a higher boiling point? If you ...

Answered by Melissa K. • Chemistry tutor

38517 Views

NaOH is a strong base. An aqueous solution is made containing 0.300mol.dm^-3 of NaOH at room temperature. Calculate the pH of this solution.

Concentration of NaOH=Concentration of OH- ions (NaOH is a strong base)

Kw=1x10^-14 (at room temperature/25 degrees)

using Kw=[H+][OH-]

We can figure out the [...

Answered by Nadine K. • Chemistry tutor

15973 Views

What is an optical isomerism?

Optical isomerism is a type of stereoisomerism which includes a chiral carbon. This means the pair of molecules have the same structural formula but the four different groups around the carbon atom are...

Answered by Nadine K. • Chemistry tutor

3247 Views