Question

I really need some help with this. My teacher explained but I still don't understand, can someone solve and explain the question for me? MUCH APPRECIATED!

1)A nutritional supplement contains 0.405 g of CaCO3. The recommended daily value of calcuim is 1.00g Ca.
Find the mass in grams of calcium in 0.405g CaCO3. What percentage of the daily value of calcium comes from this tablet?

Answer 1

0.405 g CaCO3 (1mol CaCO3/100.0869 g CaCO3)(1 mol Ca/1 mol CaCO3)(40.078 g Ca/1 mol Ca) = 0.162 g Ca

(0.162/1.00) = 16.2 %

Answer 2

Thank you so much TeyGee! Could you help me with these other few too? I would be soooo grateful! :)

(1)
A solution was made by dissolving 8.20g sodium phosphate (Na3PO4) in water and then diluting to achieve a total volume of 100.0 mL. What is the solution's molarity?

(2) The neutralisation reaction between nitric acid and potassium hydroxide is:
HNO3(aq) + KOH(aq) --> KNO3(aq) + H2O(l)
What is the minimum volume of 1.50M HNO3 needed to completely react with 0.125 L of 0.501 M KOH?
Hint: determine moles of KOH --> stoichiometric ratio of HNO3/ KOH from balanced equation --> determine number moles HNO3 --> determine volume HNO3.

(3) The neutralisation reaction between sulfuric acid and potassium hydroxide is:
H2SO4(aq) +2 KOH(aq) --> K2SO4(aq) + 2H2O(l)
What is the minimum volume of 1.50M H2SO4 needed to completely react with 0.125 L of 0.501 M KOH?
Hint: determine moles of KOH --> stoichiometric ratio of H2SO4/ KOH from balanced equation --> determine number moles H2SO4 --> determine volume H2SO4.

I WOULD BE SO GRATEFUL!!! :')

Answer 3

I'd be happy to help you but I have class :( I'll copy your questions and solve them :) I'll go online as soon as I get home from school and lab work :)

Answer 4

I'm from another time zone, BTW. If you're wondering.

Answer 5

Oh that's alright! Just solve them and I'll log back on later to get them! :') Thanks so much! Have a GREAT day! :)

Answer 6

1). 0.500 M soln
2) 0.04175 mL of HNO3
3) 0.020875 mL H2SO4

Answer 7

could you provide working for these answers please!!? need it done in 2 hours time :/ HELP! D:

Answer 8

PLEASE PLEASE PLEASE D: You've been such a big help, I need the working for the last three answers you did urgently! D:

Answer 9

Hey, could you please show working? THANKS X