The standard molar heat of vaporization for water is 40.79 kJ/mol. How much energy would be required to vaporize 6.61 ×1010 molecules of water? Answer in units of kJ

Well Barclay, we just don't do homework for you. Look at the question. Looks like a basic math question with 1010 Moles? Instead of molecules?

I think the OP means 6.1 x 10^10 molecules of water, although that's an extremely small amount of water. Barclay - simply convert that number of molecules to moles (divide by Avogadro's number) and you're 90% done.