1. volume of carbon dioxide gas obtained at STP by the complete decomposition of 9.85g sodium carbonate is in how many litres?
 
2. 1 L of carbon dioxide gas is passed through red hot coke. the volume becomes 1.4 L at same temperature & pressure. What is the composition of the products ( in L ) ?
 
3. what is the mole fraction of solvent in aqueous solution of sodium hydroxide having molality of 3 ?
 
4. concentrated aqueous sulphuric acid is 98% sulphuric acid by mass & has a density of 1.80gm/L. what is the volume of acid required to make 1 L of 0.1M sulphuric acid solution?

Asked by OM mohapatra | 1st Aug, 2014, 11:00: AM

Expert Answer:

Dear om.smaran.mohapatra@gmail.com

Thanks for asking us a question in Ask the Expert section of TopperLearning.com.

We cannot entertain more than 5 questions in a subject per day. In case of multiple questions within a query, please post each question individually and let us know where you are getting stuck so that we would be able to explain things better.
 
However, answer to your first query is,
 

1. The reaction is given as:

Na2CO→ Na2O + CO2 

Therefore, 1 mole of Na2CO3 gives = 1 mole of CO2 

That is, 105.98 g of Na2CO3 gives = 44g of CO2 

​9.85 g of Na2CO3 ​gives = 44105.98 × 9.85 g 

                                  = 4.0894 g of CO2 

Therefore,
Number of moles of CO2 produced  = Mass/Molar mass

                                                   = 4.0894/44

                                                   = 0.0929 moles

1 mole of CO2 gas = 22.4 L
0.0929 moles of gas At STP = 22.4 × 0.0929 L

                                        = 2.0809 L of CO2 would be obtained.

Regards

Topperlearning Team.

Answered by Hanisha Vyas | 1st Aug, 2014, 11:14: AM