Jewlzeh

My chemistry teacher gave me an assignment and there's a table to convert things. One is turning 28.3 g/L of Ca(NO3)2 to mol/L to % (mass/mass)

I have the mol/L as 0.172 but for the percentage, i know that its mass of solute (g) over mass of solution (g) times 100 ...

does that mean it's 28.3/1000 x 100, or is it 28.3/1028.3 x 100, since the final solution will contain both the 1L of water and the 28.3g of solute?

help is very much appreciated :)

I'm having some trouble with two of these questions, where I'm meant to write a balanced ionic equation for the reaction.

1. Lead oxide (PbO2) is added to solid sodium hydroxide.

2. Lead oxide (PbO2) is added to ethanoic acid

So I have 4 unknown solutions of Na2CO3, NaOH, NaCl and Na2SO4 (as in, i dont know which is which). If I mix these with H2SO4, how will it help me distinguish one another (or at least partly)? I can't figure out what will happen.

H2SO4 isnt the only solution i can mix the unknowns with, but the other ones don't help me find which is sodium carbonate and sodium hydroxide.

If the stair climber had eaten half a regular pizza earlier that day, they would have gained 1.58x10^6 J of chemical energy. How long must they continue to climb the stairs to 'burn off' this energy? Assume your body is 50% efficient at converting chemical energy to kinetic energy.

I know the potential energy of the climber (54x9.8x2.89 = 1529), but i have no idea what to do with this question. Help! ):

Kay guise, so I just need an answer to this. It's taken straight from my assignment:

Number of moles of hydrogen atoms (H) in 8.75 x 10^21 molecules of hydrogen has (H2)