Question

0.2g of NAOH is dissolved in 500ml of water. what is the ph of resulting solution. ​

Answer 1

Answer:

Total volume= 500+200=700ml

Mass of NaOH in 0.2M solution

⇒0.2=

200/100

x/40

⇒x=

1000

0.2×200×40

=1.6g

500ml solution contains 20g

∴ Total mass of NaOH in 700ml solution= 20+1.6=21.6g

∴ Molarity=

700/1000

21.6/40

=0.77M

Answer 2

Answer:

The pH of the solution is 12

Explanation:

Given that,

Mass of NaOH dissolved=0.2gm

Volume of water=500ml

We know that,molecular mass of NaOH=40gm

Therefore the concentration of this solution can be found using relation

$[OH {}^{ - } ] = \frac{mass \: of \: solute}{molecular \: weight} \times \frac{1000}{volume(in \: ml)}$

substituting known values,we get

$[OH {}^{ - } ] = \frac{0.2}{40} \times \frac{1000}{500} = 0.01$

The pOH of solution can be found using relation,

$pOH = - log[OH {}^{ - } ] = - log0.01 = 2$

Hence,The pH of solution is

$pH = 14 - pOH = 14 - 2 = 12$

Therefore,the pH of the solution is 12

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