Answer:
Step-by-step explanation:
#3 Here basically you have to convert the mg to g first because we want to know the number of g of calcium per glass. That comes out to be 305/1000= 0.305g. So then, now you have to set up a algebraic equation
0.305x=1.3 (basically x refers to number of glasses)
x= 4.26 (now we know the kid needs to drink about 4 glasses/cups per day)
#4
Here convert moles to grams using molar mass of NaCl.
12.5molesx58.44g/mol -------> 730.5g NaCl
#5
So any gas at STP occupies 22.4 liters/1mol of gas.
110L x 1mol/22.4L = 4.91 moles N2
#6
So here basically do the same thing as 5 to find the moles. Then multiply that moles with 6.022x10^23 molecules (because 1 mol has 6.022x10^23 molecules) to find the number of molecules.
You should get 1.21x10^25 molecules
#7
Here basically find the moles first then convert the moles to grams using molar mass of H3PO4.
Molarity=moles/volume
1.7= x/0.550 -----(here we converted ml to L because volume is in liters for molarity)
x= 0.935 moles
Then, 0.935mol x 97.994g/1mol = 91.6g H3PO4
#8
Here convert the grams to moles using molar mass first (divide the grams by the molar mass) then multiply the number which is moles by 6.022x10^23 molecules (because 1 mol has 6.022x10^23 molecules) to find the number of molecules.
You should get 2.77x10^24 molecules
Hopefully everything makes sense lmk if it doesn't...I have tried my best to do these quickly I am sorry for any errors.