Calculate the molarity of each aqueous solution: a. 78.0 ml of 0.240 m naoh diluted to 0.250 l with water b. 38.5 ml of 1.2 m hno3 diluted to 0.130 l with water

We know that when we dilute a solution the number of moles remains the same just the concentration changes [moles per unit volume]

So we can equate the moles before dilution and after dilution

moles = molarity X volume

a) Initial moles = final moles [NaOH]

M1= initial molarity = 0.240 M

V1= initial volume = 78 mL

M2= final molarity = ?

V2 = final volume = 0.250 L = 250mL

therefore

final molarity = 0.075 M

b)

Initial moles = final moles [Nitric acid]

M1= initial molarity = 1.20 M

V1= initial volume = 38.5 mL

M2= final molarity = ?

V2 = final volume = 0.130 L = 130mL

therefore

final molarity = 0.355 M

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.