Textbook 6B 11

[Natalie Vu 1I]

I think I'm confused on how to use all the different volumes in order to solve the problem. I know how to get ai) but not aii) and b.

[AudreyQian1J]

Hello,
For a(ii), we are given information on the final volume (500 mL) and initial volume (5.00 mL) of the original solution, and we have already calculated the the final concentration of hydroxide ions (0.18M). We can use the equation M1V1=M2V2 to calculate for M1, the concentration of hydroxide ions in the original solution.

For (b), we use the balanced equation of the reaction: Na2O + H2O <--> 2NaOH to calculate the mass of Na2O using stoichiometry, starting from converting the concentration of the hydroxide ions in the original solution to moles and then to moles of Na2O, where we can then calculate its mass. Remember that when converting the NaOH concentration to moles, multiply by 0.200 L because Na2O + H2O make up a 200.0 mL volumetric flask.

I hope this helps.