Answer:
The percent composition is 21% N, 6% H, 24% S and 49% O.
Explanation:
1st) The molar mass of (NH4)2SO4 is 132g/mol, and it represents the 100% of the mass composition.
In 1 mole of (NH4)2SO4, there are:
- 2 moles of N.
- 8 moles of H.
- 1 mole of S.
- 4 moles of O.
2nd) It is necessary to calculate the mass of each element, multiplying its molar mass by the number of moles:
- 2 moles of N (14g/mol) = 28g
- 8 moles of H (1g/mol) = 8g
- 1 mole of S (32g/mol) = 32g
- 4 moles of O (16g/mol) = 64g
3rd) With a mathematical rule of three we can calculate the percent composition of each element in the molecule of (NH4)2SO4:




In this case, we can calculate the percent composition of Oxygen by subtracting the other percentages, since the total must be 100%.
So, the percent composition is 21% N, 6% H, 24% S and 49% O.
Answer:
Theoretical yield of hydrogen is 1.11 g
Explanation:
Balanced equation, 
As Mg remain present in excess therefore HCl is the limiting reagent.
According to balanced equation, 2 moles of HCl produce 1 mol of
.
Molar mass of HCl = 36.46 g/mol
So, 40.0 g of HCl =
of HCl = 1.10 moles of HCl
Hence, theoretically, number of moles of
are produced from 1.10 moles of HCl = 
Molar mass of
= 2.016 g/mol
So, theoretical yield of
= 
Hydrogen peroxide breaks down into water and oxygen.
2H₂O₂ → 2H₂O + O₂
The yeast present contains an enzyme called catalase which catalyses the reaction.
More the amount of the catalyst added, faster will be the decomposition of the hydrogen peroxide.
Thus if we added more than 5 mL of yeast solution to the 2H₂O₂, the breakdown would occur faster. Thus the bubbles and the accompanying fizz would be much more.
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Answer: B. a chemical change
Explanation:
There are 0.000076 moles in 4.6 x 10^19 atoms.