The formula mass of aluminum oxalate Al_2(C_2O_4)_3 is 182 amu 318 amu 156 amu 2
ID: 1052891 • Letter: T
Question
The formula mass of aluminum oxalate Al_2(C_2O_4)_3 is 182 amu 318 amu 156 amu 245 amu 283 amu A 1.195 g sample of an element contains 6.668 times 10^21 atoms. What is the element symbol? Ag Sb Sn Te Ba What is the mass in grams of one propane, C_3 H_8 molecule? 44.0 7.32 times 10^-23 g 2.64 times 10^25 g 42.0 g 1.99 times 10^23 g How many molecules are there is 60.0 g of acetic acid, C_2H_4O_2? 6.02 times 10^23 (6.02 times 10^23)/60.0 60.0 times (6.02 times 10^23) 30.0 60.0 How many aluminum atoms are there is 63 g of Al_2S_3? 5.1 times 10^23 1.9 times 10^21 7.6 times 10^23 2.5 times 10^23 1.3 times 10^21Explanation / Answer
Ans. 1. Al2(C2O4)3 = 318.02 g mol-1 = 318 amu
1 amu = 1 g/ mol
Ans. 2.
6.668 x 1021 atoms weigh 1.195 gram
Or, 1 atom - (1.195 / 6.668 x 1021) gram
Or, 6.022 x 1023 (1.195 / 6.668 x 1023) , 6.022 x 1023 gram
= 107.9 gram
So, atomic mass of the element = 107.9 g mol-1
It is Ag (atomic mass = 107.87 g/ mol)
Ans. 3. Molecular mass of C3H8
= 4 x (12.011) + 8 x (1.00) = 44.096 g mol-1
1 mol = 6.022 x 1023 molecules
Mass of 1 molecular = 44.0 g / (6.022 x 1023) = 7.30 x 10-23
Approx. equal to 7.32 x 10-23 g
Ans. 4. Molecular mass of acetic acid = 60.0 g mol-1
Number of moles of acetic acid in 60.0 gram sample = mass/ molecular mass
= 60.0 g / (60.0 g mol-1) = 1 mole
Since, acetic acid is 1 mole; number of molecules = 6.022 x 1023 molecules
Ans. 5. Number of moles of Al2S3 = mass / molecular mass
= 63.0 g / (150.14 g mol-1)
= 0.4196 moles
Each molecule has 2 atoms of Al, so number of moles of Al = 2 x 0.4196 moles = 0.83921 moles
Number of Al atoms = mole x Avogadro number
= 0.83921 moles x 6.022 x 1023 = 5.05 x 1023atoms
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