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Explain what is meant by the term 'buffer solution' and give an example of a biological buffer system.

A buffer solution is a solution which resists changes in pH when small quantities of acid or alkali are added to it. An example of a biological buffer system would be the bicarbonate buffer system (regulates...
RB
Answered by Ruby B. • Chemistry tutor
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Calculate the pH change when water is added to 25.0 ml of 0.250M NaOH to form a 1.00l solution.

The initial [-OH] is 0.250M since NaOH releases 1 mole of -OH per mole of base. Using Kw=[H+][-OH], [H+]=(1 10 -14 )/0.250=4 10 -14 M (note remember units). Hence the initial pH=-log(4 10 -14 )=13.4 (note 3 ...
MS
Answered by Milind S. • Chemistry tutor
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Calculate the pH of the solution formed when 30 cm3 of 0.150 moldm-3 aqueous sulfuric acid is added to 30 cm3 of 0.200 moldm-3 aqueous potassium hydroxide at 25 C.

H 2 SO 4 ---> 2H + + SO 4 2- KOH ---> OH - + K + Initial moles of Sulfuric acid: Volume x Concentration = Moles (30/1000) x 0.150 = 4.5x10 -3 mol Moles of H + made by sulfuric acid: It is a 1:2 ratio o...
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Answered by William D. • Chemistry tutor
15814 Views

Define the term relative isotopic mass. (2 Marks)

Mass of the isotope/atom compared to 1/12th the mass of an atom of Carbon 12 (12C)
TD
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The following equilibrium is set up in a glass syringe. 2(NO2) (brown gas) ‹-› N2O4 (colourless gas) ∆H = -58 kJmol-1. Using le Chatelier's principle, predict and explain how heating up the mixture would affect it's appearance.

At first this question can seem confusing, but by breaking it down we can better understand what we are being asked to do. Firstly, we need to recall le Chatelier's principle - that an equalibrium will shift...
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Answered by Robert S. • Chemistry tutor
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