Mass of electrons are not included when calculating the atomic mass of element. Atomic mass of the element is equal to proton + neurons. Example the the mass number of Nitrogen can be calculated as 7 protons + 7 neutrons to give 14 . thus nitrogen has a mass number of 14
Answer:
27%
Explanation:
Hello,
The following information is missing, but I found it: "1.92 g of sodium sulfate is produced from the reaction of 4.9 g of sulfuric acid and 7.8 g of sodium hydroxide" so the undergoing chemical reaction is:

Now, to compute the percent yield, we must first establish the limiting reagent to subsequently determine the theoretical yield of sodium sulfate because the real (1.92g) is already given, thus, we consider the following procedure:

- The moles of sodium hydroxide that completely react with 0.05 moles of sulfuric acid are:

As this number is higher than the previously computed 0.05 moles of available sulfuric acid, one states that the sulfuric acid is the limiting reagent. Now, the theoretical grams of sodium sulfate are found via:

Finally, the percent yield turns out into:

%
Best regards.
C + H2O -> H2 + CO
n(C) = 15.9/12 = 1.325 (mol)
=> n(H2) = 1.325 mol
We have:
PV = nRT
=> V = (nRT)/P
(R = 22.4/273 = 0.082)
V = (1.325 x 0.082 x 360)/1 = 39.114 (L)
The percent of O in Cr₂O₃ : 31.58%
<h3>Further explanation</h3>
Given
Cr = 52.00 amu, O = 16.00 amu
Required
The percent of O
Solution
MW Cr₂O₃ = 2 x Ar Cr + 3 x Ar O
MW Cr₂O₃ = 2.52+3.16
MW Cr₂O₃ =152 amu
