Tag: chemistry

A certain indicator (an organic dye) has $p{K} _{a} = 5$. For which of the following titrations it may be suitable?

The amount of sodium hydrogen carbonate, $NaH{ CO } _{ 3 }$, in an antacid tablet is to be determined by dissolving the tablet in water and titrating the resulting solution with hydrochloric acid. Which indicator is the most appropriate for this titration?
Acid                  ${K} _{a}$
${ H } _{ 2 }{ CO } _{ 3 }$          $2.5\times { 10 }^{ -4 }$
${H{ CO } _{ 3} }^{ - }$           $2.4\times { 10 }^{ -8 }$

A solution containing $Na _{2}CO _{3}$ and $NaOH$ requires $300\ mL$ of $0.1\ N\ HCl$ using phenolphthalein as an indicator. Methyl orange is then added to the above-titrated solution when a further $25\ mL$ of $0.2\ N\ HCl$ is required. The amount of $NaOH$ present in the original solution is:

In the titration of ${ NH } _{ 4 }OH$ with $HCl$, the indicator which cannot be used is:

In the titration of nitric acid against potassium carbonate, the indicator used is:

A solution containing $Fe^{2+}$ ions is titrated with $KMnO _{4}$ solution. Indicator used will be:

In the mixture of $NaHCO _{4}$ and $Na _{2}CO _{3}$, volume of a given $HCl$ required is $x\ mL$ with phenolphthalein indicator and $y\ mL$ with methyl orange indicator in same titration. Hence, volume of $HCl$ for complete reaction of $Na _{2}CO _{3}$ present in the original mixture is

$40\ mL$ of $0.05\ M\ Na {2}CO _{3}\cdot NaHCO _{3} \cdot 2H _{2}O$ (sesquicarbonate) is titrated against $0.05\ M\ HCl.\ x\ mL$ of $HCl$ is used when phenolphthalein is the indicator and $y\ mL\ HCl$ is used when methyl orange is the indicator in two separate titrations, hence $(y - x)$ is_______.

$0.1\ N$ solution of $Na _{2}CO _{3}$ is being titrated with $0.1\ N\ HCl$, the best indicator to be used is:

Select incorrect statement(s) among the following.