Question

PLEASE HELP, VERY URGENT
Calculate the volume of a NaCl solution that would contain 5.0 g of NaCl and have a molarity of 4.8 M.

Calculate the pH for a solution with a 4.6 x 10-9 M hydronium concentration.

Answer 1

\(\text{Molarity} = \dfrac{\text{moles of solute}}{\text{liters of solution}}\)

In essence, molarity is moles / volume

We are told that the solution contains 5.0 g of NaCl and has a molarity of 4.8

We need to first convert grams of NaCl to moles of NaCl so that way we can calculate how many liters of solution we have

Answer 2

The molar mass of NaCl is 58.44

This means that 58.44 grams of NaCl equals 1 mole

So how many moles is 5.0 grams?

Which way would you set it up so that the grams cancel each other out leaving you with moles in the numerator?

Answer 3

Would it be the top one or the bottom one?

So how many moles of NaCl do we have?

Now remember the formula

Molarity = Moles / volume

so the molarity was 4.8
now that you have the number of moles, can you calculate the volume?

And don't forget, the units of the volume is going to be liters
If you want the volume in milliliters (mL) then you have to multiply by 1000

Answer 4

The second question is straight forward

\(\text{pH = -log[H}^+]\)

They told you that the hydronium concentration or [H+] is equal to 4.6 * 10^(-9)

To find the pH, you need to do the negative log of the hydronium concentration
i.e. take the log of it and then multiply it by -1