Need help on Chem Questions! ?

Hey all, ive done the work on some of these questions but don't know if the answers are correct. Any help for any of the following would be greatly appreciated. 

1. How many nitrogen atoms are in 3.75 moles of (NH4)3PO4? 

2. In a chemical analysis, 8.4 g of iron (III) hydroxide precipitate is collected. The amount, in moles?

3. The number of moles in 120.3 g of CoBr3 is?

4. In a chemical analysis, a 35.0 mL sample of 3.96 mol/L iron (III) chlorate solution is diluted to 300.0 mL. What is the concentration of the final solution?

5. A technician dilutes concentrated 17.4 M acetic acid to prepare 200. mL of 8.00 M stock solution. What volume of concentrated acetic acid must be used?

1 Answer

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  • david
    Lv 7
    4 weeks ago
    Favorite Answer

    1. How many nitrogen atoms are in 3.75 moles of (NH4)3PO4? 

        3.75 X 3 X 6.022x10^23  <<<  use a calculator

    2. In a chemical analysis, 8.4 g of iron (III) hydroxide precipitate is collected. The amount, in moles?  <<<  the amount of what, the precipitate?

       find molar mass Fe(OH)3 in grams

       (1mole / molar mass) X (8.4 g)  >>> use a calculator

    3. The number of moles in 120.3 g of CoBr3 is?

      /// need molar mass again . Cobr3

        (1mole / molar mass) X (120.3 g)

    4. In a chemical analysis, a 35.0 mL sample of 3.96 mol/L iron (III) chlorate solution is diluted to 300.0 mL. What is the concentration of the final solution?

       ( 3.96 mol/L) X (35.0mL/300.0mL)  <<<  calculator?

    5. A technician dilutes concentrated 17.4 M acetic acid to prepare 200. mL of 8.00 M stock solution. What volume of concentrated acetic acid must be used?

       (8.00M X 200mL) / 17.4mL  >>>  calculator

         

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