Answer: 88.2 g
Solution:
1) Chemical equation:
<span>2Al (s) + 3Fe(NO3)2 (aq) → 3Fe (s) + 2Al(NO3)3 (aq)
2) Theoretical molar ratios
2 mol Al : 3 mol Fe(NO3)2 : 3 mol Fe : 2 mol Al(NO3)3
3) Starting mass of pure iron nitrate
% = (mass of iron nitrate / mass of solution) * 100 = 87.5
=> mass of iron nitrate = 87.5 * mass of solution / 100
mass of solution = 325 g
=> mass of iron nitrate = 87.5 * 325 g / 100 = 284.375 g
4) moles of iron nitrate
moles = mass in grams / molar mass
molar mass of Fe(NO3)2 = 179.85 g/mol
moles = 284.375 g/ 179.85 g/mol = 1.58 moles Fe(NO3)2
5) proportion:
x 3 mol Fe
--------------------------- = ----------------------
1.58 mol Fe(NO3)2 3 mol Fe(NO3)2
Clear x:
x = 1.58 mol Fe
6) Convert 1.58 mol Fe into grams
mass = number of moles * atomic mass
atomic mass of iron = 55.845 g / mol
mass = 1.58 moles * 55.845 g/mol = 88.24 g
Rounded to 3 significant figures: 88.2 grams of Fe.
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Answer:
I think it is either a or b
Explanation:
c or d has the correct names and Roman numerals.
There are approximately 6.02 × 10²³ atoms of phosphorus in one mole of 30.974 grams of phosphorus (option A).
<h3>How to calculate number of atoms?</h3>
The number of atoms of a substance can be calculated by multiplying the number of moles of the substance by Avogadro's number. That is;
no of atoms = no of moles × 6.02 × 10²³
According to this question, there are 30.974 grams of phosphorus in one mole of phosphorus. The number of atoms can be calculated as follows:
no of moles of P = 30.974g ÷ 31g/mol = 0.99mol
number of atoms = 0.99 mol × 6.02 × 10²³
number of atoms = 6.02 × 10²³ atoms
Therefore, there are approximately 6.02 × 10²³ atoms of phosphorus in one mole of 30.974 grams of phosphorus.
Learn more about number of atoms at: brainly.com/question/8834373
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Answer:
Molar heat enthalpy of KBr = -19.89 kJ/mol
Explanation:
Change in temperature (Δt) = 0.370 K
Heat capacity = 2.71 kJ ⋅ K^-1
Heat absorbed by calorimeter = heat capacity × change in temperature
= 2.71× 0.370
= 1.0027 kJ
Molar mass of KBr = 119 g/mol
No. of moles of KBr = 6.00/119
= 0.0504 mol
Heat absorbed by the calorimeter is given by KBr.
Now calculate the heat released by per mol of KBr as follows:
Heat released by per mol of KBr = 1.0027 kJ / 0.0504 mol
=19.89 kJ/mol
Heat is released therefore, sign will be negative.
Molar heat enthalpy of KBr = -19.89 kJ/mol
