Answer: Stoichiometry is the process of comparing the individual qualitative or numerical variables of the reactants or products involved in a chemical reaction.
Explanation:
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1) Chemical reaction:
Fe2O3 + 2Al ---> Al2O3 + 2Fe
2) molar ratios
1 mol Fe2O3 : 2Al : 1 mol Al2O3 : 2 mol Fe
3) Convert 15.0 g of iron into moles
atomic mass Fe = 55.8 g/mol
moles = mass in grams / atomic mass = 15.0 g / 55.8 g/mol = 0.269 mol
4) Use proportions to determine the moles of Fe2O3, Al, and Al2O3
a) 1mol Fe2O3 / 2 mol Fe = x / 0.269 mol Fe
x =
=> x = 0.269 mol Fe * 1 mol Fe2O3 / 2 mol Fe = 0.134 mol Fe2O3
b) 2 mol Al / 2 mol Fe = x / 0.269 mol Fe
=> x = 0.269 mol Al
c) 2 mol Fe / 1 mol Al2O3 = 0.269 mol Fe / x
=> x = 0.269 mol Fe * 1 mol Al2O3 / 2 mol Fe
x = 0.134 mol Al2O3
5) Convert moles to grams
a) Fe2O3
molar mass Fe2O3 = 2* 55.8 g/mol + 3*16g/mol = 159.6 g/mol
mass = molar mass * number of moles
mass = 159.6 g/mol * 0.134 mol = 21.4 g
b) Al
atomic mass = 27.0 g/mol
mass = number of moles * atomic mass = 0.269 mol * 27.0 g/mol = 7.26 g
c) Al2O3
molar mass = 2 * 27.0 g/mol + 3*16.0 g/mol = 102.0g/mol
mass Al2O3 = numer of moles * molar mass = 0.134 mol * 102.0 g/mol = 13.7 g
Answers:
21.4 g Fe2O3
7.26 g Al
13.7 g Al2O3
Given data: <span>molar mass = 180.2 g/mol in 920.0 ml of water at 25 °c.
</span><span>the vapor pressure of pure water at 25 °c is 23.76 mm hg.
</span>Asked: <span>the vapor pressure of a solution made by dissolving 109 grams of glucose
</span><span>
Solution:
moles glucose = 109 g/ 180.2 g/mol=0.605
mass water = 920 mL x 1 g/mL = 920 g
moles water = 920 g/ 18.02 g/mol=51.1
mole fraction water = 51.1 / 51.1 + 0.605 =0.988
vapor pressure solution = 0.988 x 23.76 = 23.47 mm Hg</span>