1.

An environment chemist needs a carbonate buffer of `pH=10` to study the effects of the acidification of limestones rich solis.How many grams of `Na_(2)CO_(3)` must be added to `1.5L` of freshly prepared `0.2M NaHCO_(3)` to make the buffer.? For `H_(2)CO_(3),K_(a_(1))=4.7xx10^(-7),K_(a_(2))=4.7xx10^(-11)`

Answer» `pK_(a)=11-log4.7`
`pK_(a)=11-log4.7`
`pH=pK_(a)+log((n_(Na_(2)CO_(3)))/(0.3)):.10=11-log4.7+log((n_(Na_(2)CO_(3)))/(0.3))`
`log((4.7xx0.3)/(n_(Na_(2)CO_(3))))=1rArr n_(Na_(2)CO_(3))=0.141`
`W_(Na_(2)CO_(3))=0.141xx106=14.946~~15 gram`.


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