Jump to content

Kinetics P2 Questions

Recommended Posts

QS: 

The rate expression for this reaction is rate = k [N2O]2 and the rate constant is
0.244 dm
3 mol–1 s–1 at 750 °C.

 A sample of N2O of concentration 0.200 mol dm–3 is allowed to decompose. Calculate the rate when 10 % of the N2O has reacted.

ANS: 

0.9 × 0.200 = 0.180 (mol dm–3);

rate = (0.244 × (0.180)2 =) 7.91 × 10–3 mol dm–3 s–1

 

Why do we have to times 0.9 to 0.200? I thought since 10% has reacted, 0.1 should be times instead of 0.9.

Please help me clarify this question.

Thanks alot

Share this post


Link to post
Share on other sites

The concentrations used in rate calculation are how much are present. If 10% has been consumed then the concentration of N2O remaining is 90% of starting concentration.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.