[Solver0603]

As a birthday balloon is filled with helium, the amount of helium increases from 0.5 moles of helium to 5.5 moles of helium. If the initial volume of the balloon is 2.5 mL, what is the final volume?

What is the mass of sodium chloride used to create a 100 mL solution at a concentration of 1.5 M?

[Borek]

You have to show your attempts at solving the problem to receive help, this is a forum policy.

[Vidya]

For  first question use Avogadro's law
For the second question use molarity equation
Remember molarity is moles per litre

[Fudjsk]

"As a birthday balloon is filled with helium, the amount of helium increases from 0.5 moles of helium to 5.5 moles of helium. If the initial volume of the balloon is 2.5 mL, what is the final volume?"

For this problem, you could use a ratio between the original number of moles, the original volume and the final number of moles in order to find the final volume.

Volume units do not need to be standardized because the problem does not require the ideal gas formula.
In the end. n1/V1=n2/V2 where n= moles and V=volume.