
Demand
Implies Urgency
 Using 'demand' suggests you can't wait much longer for a response. 
The workers' demand for better conditions was urgent.
 Often Assertive
 Can be seen as assertive or even aggressive, especially in personal situations. 
She demanded an apology immediately.
 Confusion with 'Ask'
 'Demand' is much stronger than 'ask'; use it when 'ask' is too mild. 
He didn't just ask for silence; he demanded it.