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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 ...
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Answered by Milind S. • Chemistry tutor
17623 Views

Describe the structure of a protein

All proteins are polymers of amino acids arranged with varying degrees of complexity. The most basic structure is the order of amino acids, this is called the primary structure. Amino acids form peptide bond...
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Answered by Sam C. • Biology tutor
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Briefly explain how Darwin formulated his theory of evolution by natural selection.

Darwin made four key observations in his studies of wild populations: members of a population of the same species vary in their traits; traits can be inherited, or passed from parents to offspring; populatio...
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Answered by Zak L. • Biology tutor
3826 Views

2x^2-6x+5 can be written in the form a(x -b)^ 2 + c where a, b and c are positive numbers. Find a,b and c.

In order to solve this problem we must first complete the square. To complete the square we need to factorise the equation to get the coefficient of x to be 1. This gives: 2(x^2-3x)+5. We then need to comple...
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Answered by Chloe H. • Maths tutor
24399 Views

Asses the view that political factors best explain the American withdrawal from Vietnam.

The Vietnam War was a humiliating defeat for America. It was the first televised war which significantly changed how the U.S. public viewed international conflict and has remained an embarrassing debacle for...
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Answered by Phoebe G. • History tutor
6706 Views