How do I find how many moles of hydrogen atoms...?

Question

1: How many moles of hydrogen atoms are there in:
a) 1.60 moles of zinc hydroxide
b) 0.20 moles of sodium hydrogenphosphate-12-water

Also, how do I find the mass of the following samples?
a) 2.65 moles of phosphoric acid, H3PO4

b) 0.0080 moles of mercury (II) iodide

c) 1.60 moles of yellow phosphorous, P4

Please help me. Thankyou.
c) 0.350 moles of ammonium hydrogensulfate

Note: How do I do this...please explain it all to me and show working so that I know how to do these. Do I need to know the formula for these 1st question ones? Please help me.

1.
c) 0.350 moles of ammonium hydrogensulfate

(I forgot to type it in to the 1st question)...

is 1. a)=3.2 moles of H atoms?

Cattbarf, the example I am given with the answer is: How many moles of oxygen atoms are ther in 2.5 moles of glucose (C6H12O6)
=6* moles of glucose
=6*2.5
=15 moles of oxygen atoms.

This leads me to believe that number 1. a)=3.2 moles of H atoms not 1.6 as you have stated. Please justify your 1st answer. Thankyou.

They are wanting H atoms not molecules which are obviously diatomic! Look at the example I put with the correct answer in the added details area. Oxygen is also present in the atmosphere as a diatomic molecule. Look at the example and answer. That is correct by the way.

Answer 1

moles=grams/atomic mass

atomic mass of H is about 1 so one gram equals one mole. Thats only for H though

Answer 2

You MUST know the formulas to answer Q1.
a. The compound is Zn(OH)2.
Since hydrogen appears as H2, 1 mole of hydrogen supplies 2 g-atoms. In this case, you HAVE 2 g-atoms in the hydroxide, so there is one mole of H2 per 1 mole of the compound. Ans=1.6
b. The compound is Na H2PO4 (phosphoric acid has 3 ionizable hydrogens, and thus with a anion like sodium can form 3 different compounds.
Here you again have 2-atoms of the hydroxide
per mole of the compound. So Ans= 0.20
c. The compound is NH4 HSO4 . Each mole of this contains 5 g-atoms of H. So the moles in each mole is 2.5. Ans= 0.875 moles.

For your masses, you need mole weights and to know the atomic numbers of the component elements
For H3PO4, mass = 3(mass H)+ 1(mass P) + 4(mass O). The masses are 1, 35 and 16 respectively, so the answer would be 102g/mole
So multiply this by 2.65 to get mass.

The compound is HgI2.
The mass is (if I have my numbers right) is
198+2(127)= 452
Multiply by 0.008 to get mass

For P4 mass= 4P or 140. Mult by 1.6 to get answer.

Answer 3

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Answer 4

the first answer is 1.6;

[1.6 moles Zn(OH)2] TIMES [2 mol OH/1 mol Zn(OH)2] TIMES [1 mol H/2 mol OH] = 1.6 mol H2

the equations i used for that: Zn + (OH)2 --> Zn(OH)2

and: H2 + 2O --> (OH)2

remember: hydrogen is diatomic. when isolated, it only comes as H2. that is the reason why the answer can't be 3.2 grams H

Answer 5

1. a) 1.60 mol Zn(OH)2, 1 mol Zn(OH)2 = 2 mol H
1.60 mol Zn(OH)2 x (2mol H/1mol Zn(OH)2 )
= 3.20 mol H
b) NaH2PO4.12H2O
0.20 mol NaH2PO4.12H2O x (26 mole H/ 1mol NaH2PO4.12H2O) =5.2 mol H

2. a) 2.60 mol H3PO4 x (98.0 g/mol)=254.8=255 g
b) 0.0080 mol HgI2 x (454.4g/mol) =3.6 g
c) 1.60 mol P4 x(124g/mol)=198g
3. 0.350 mol NH4HSO4 x (115g/mol)=40.3 g