CH302 Chapter 7 notes part 1 answers

CH302 Chapter 7 notes part 1 answers - -12 was it basic or...

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1 In a solution it was found that [H + ] = 2.34x10 -4 M What is [OH - ] ? [OH - ] = 1 x 10 -14 M 2 / [H + ] = 1 x 10 -14 M 2 / 2.34 x 10 -4 M = 4.27 x10 -11 M Is this solution basic or acidic? Acidic Example: Consider two solutions, one with pH = 7.8 the other pH = 9.3 How much more acidic is the first one than the second? first solution: [H+] = 10 -7.8 = 1.585 x10 -8 M, second: [H+] = 10 -9.3 = 5.012 x10 -10 M dividing: 1.585 x10 -8 M / 5.012 x10 -10 M = 31.6 times more acidic -- the pH changed by 1.5 units, each change of one unit is a factor of 10. Example If a solutions’ pH is adjusted so that it increases by 0.7 units then what is the new [H+] if the original pH was 11.2? The new pH = 11.2 + 0.7 = 11.9 The new [H + ] = 10 -11.9 = 1.259 x 10
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Unformatted text preview: -12 was it basic or acidic? did it become more basic or more acidic? Example: We have a 0.03M solution of nitric acid, HNO 3 . What is the pH? [H + ] = [HNO 3 ] 0 = 0.03M pH = - log (0.3) = 1.5228 If this had been a 0.03M solution of a WEAK acid, not all the acid would have dissociated, so pH would be GREATER than 1.5228 (less acidic). We'll see how to do this next. Example 1: We have a 0.25M solution of sulfuric acid, H 2 SO 4 . What is the pH? Extra bit to note: Sulfuric acid contains TWO protons so, H 2 SO 4 2H + + SO 4 2-This means that [H + ] = 2 x 0.25 = 0.5M pH = - log (5x10-1 ) = 0.301 yes, you can have pH's below 1. . its very acidic! Example:...
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This note was uploaded on 06/13/2011 for the course CH 302 taught by Professor Holcombe during the Spring '07 term at University of Texas.

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