Chemistry HW help? I don't understand!?

I keep forgetting how to do these types of problems! Help me please! 1) How many molecules are in 250 g of water? ?molecules= 250 g H2O (that's how we set it up in our class) 2) How many potassium atoms are in 6.5 mol of Potassium Carbonate? ? atoms= 6.5 mol K2CO3 (is formula right?) Please explain... show more I keep forgetting how to do these types of problems! Help me please!

1) How many molecules are in 250 g of water?
?molecules= 250 g H2O (that's how we set it up in our class)

2) How many potassium atoms are in 6.5 mol of Potassium Carbonate?
? atoms= 6.5 mol K2CO3 (is formula right?)

Please explain in detail! Thanks :)
2 answers 2