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1. A solution of ammonia is 2.0% ionized at 25.0 degrees celsius.What was the or

ID: 684324 • Letter: 1

Question

1. A solution of ammonia is 2.0% ionized at 25.0 degrees celsius.What was the original concentration ( in M) of the ammoniasolution? The Kb at 25.0 degrees celsius for ammonia is4.8 x 10-5.

The answer to this question is 4.41 x 10-2. Pleaseexplain the calculation steps (SIMPLY) of how to get to thisanswer.
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2. Selenous Acid, H2SeO3, is a weak diproticacid. A 0.10 M solution of sodium hydrogen selenate willbe________. Ka = 2.3 X 103, Ka2 =5.3 x 109. Choose One Answer butExplain why you chose it.

A. Acidic
B. Neutral
C. Basic
D. Insufficient Information to determine.

Explanation / Answer

We Know that :       NH3 +H2O ------> NH4+ +OH-     I:  M                               0        0      C: -x                        +x            +x      E : M-x                  +x               +x                                                                 Kb = 4.8 x 10-5.                                                                 1.8 x 10-5. = [ x ]2 / [M-x ]               ignoring the value M-x we have get the value of x as 0.00692               x / M x 100 = 2.0               0.00692 / M x 100 = 2.0                   intial concentration of the base taken = 0.346 M b.          As theselenous acid is a weak acid the given concentration of sodiumselenate it behaves as strongly basic in           natureit ionizes to give the basic solution in the presence of baseNaOH.