Chat with tutor

Ask Questions, Get Answers


What would be the molality of a solution obtained by mixing equal volumes of 30% by weight $H_2SO_4$ ($d=1.218gml^{-1}$) and 70% by weight $H_2SO_4$ ($d=1.610gml^{-1}$)?If the resulting solution has density 1.425g/ml,calculate its molarity.


1 Answer

Step 1:
Let $V$ml of each are mixed.
$H_2SO_4$ is 30% by weight
Wt of $H_2SO_4=30g$
Wt of solution =100g
Volume of solution=$\large\frac{100}{1.218}$$ml$
(i.e) $\large\frac{100}{1.218}$$ml$ contains 30g $H_2SO_4$
$\therefore$ Vml contains $\large\frac{30\times V\times 1.218}{100}$ of $H_2SO_4$
Step 2:
$H_2SO_4$ is 70% by wt.
$\therefore$ Wt of $H_2SO_4$=70g
Wt of solution =100g
Volume of solution =$\large\frac{100}{1.610}$ml
(i.e) $\large\frac{100}{1.610}$ml contains 70g $H_2SO_4$
$V$ml contains $\large\frac{70\times V\times 1.610}{100}$g $H_2SO_4$
On mixing these two,total wt of $H_2SO_4=\bigg[\large\frac{30\times 1.218}{100}+\frac{70\times 1.610}{100}\bigg]$$Vg$
$\Rightarrow 1.4924Vg$
Step 3:
Total volume of solution =2Vml
Molarity of solution =$\large\frac{1.4924V}{98\times \Large\frac{2V}{1000}}$
$\Rightarrow 7.61$
Now wt of total solution $=2V\times 1.425g$
$\Rightarrow 2.85Vg$
Wt of water =(2.85V-1.4924V)g
$\Rightarrow 1.3576Vg$
Molality of solution =$\large\frac{1.4924V}{98\times \Large\frac{1.3576V}{1000}}$
$\Rightarrow 11.22$
Hence (b) is the correct option.
Help Clay6 to be free
Clay6 needs your help to survive. We have roughly 7 lakh students visiting us monthly. We want to keep our services free and improve with prompt help and advanced solutions by adding more teachers and infrastructure.

A small donation from you will help us reach that goal faster. Talk to your parents, teachers and school and spread the word about clay6. You can pay online or send a cheque.

Thanks for your support.
Please choose your payment mode to continue
Home Ask Homework Questions
Your payment for is successful.
Clay6 tutors use Telegram* chat app to help students with their questions and doubts.
Do you have the Telegram chat app installed?
Already installed Install now
*Telegram is a chat app like WhatsApp / Facebook Messenger / Skype.