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Molecular Mass
Molecular mass measures the mass of a molecule. It is measured by adding together the atomic masses of atoms the molecule is made of.
617 Questions
How many moles aluminum exist in 100.0 grams of aluminum?
The formular you need is M = n/m (molar mass = amount of substance/mass), or n = m/M
Aluminium has a molar mass of 26.982 g/mol. The given mass is 3 grams. Therefore:
n(Al) = 3g / (26.982g/mol) = 0.11mol
How much would 4 moles weigh in grams?
Answering this question is impossible since the quantity "mole" is always related to some chemical substance.
One mole of a substance is defined as about 6.022 * 10^23 units of this substance. For example one mole of H2O consists of 6.022 * 10^23 molecules of H2O. On mole of beer bottles is made up by 6.022 * 10^23 bottles of beer. Obviously one mole of beer bottles is a bit heavier then on mole of water.
The exact mass of a mole of a substance is derived from its molecular weight. the factor of 6.022 * 10^23 (the Avogadro-number) converts the atomic mass to the mass in grams.
One molecule of CaCO3 has the atomic mass of (40 + 12 + 3 * 16) u = 100 u.
Thus one mole of CaCO3 has the mass of 100 g.
4.26 g for instance equal to 2.113 moles of H2 (having an molecular weight of 2.016 u).
How do we get moles from mass?
One mole of a molecule or element is related to the molecular weight of the molecule. Thus the molecular weight of water H2O is 1+1+16 (the atomic weights of the atoms in one molecule of water) is 18 grammes.
The actual figure is slightly different since for more accuracy all atoms have slightly under or slightly over what you'd expect.
This is because of the presence of isotopes and the fact that all atomic weights are based around carbon 12, being exactly 12.00000. But on the periodic table carbon appears as 12.0107 because of the presence of it's isotope carbon 14 (2 more neutrons in it's nucleus).
Thus Hydrogen's atomic weight is 1.00794 - but this an average because of the isotopes of hydrogen present - deuterium and tritium. Pure Hydrogen 1, is 1.007825 slightly over 1 because of carbon 12 being the standard.
Oxygen is 15.9994, slightly below 16 again because of small amounts of 2 other isotopes and the carbon 12.0000 contribution.
So the molecular water is actually 18.01528, and so one mole weighs 18.01528g.
One mole of any element or molecule contains the Avogadro's number of atoms/molecules. Avogadro's number is 6.02214179 ×10 to the power of 23, a very large number indeed. The actual weight of a single atom or molecule can be calculated by dividing it's exact molecular/atomic weight by Avogadro's number. Thus one atom of hydrogen 1 weighs 1.6735245 x 10 to the power of minus 22 grammes.
Incidentally, mono molecular water is water vapour (not steam, but the invisible bit you see coming out of a kettle spout at the boil, steam is water droplets). Water as we know it is 3 molecules bound together through hydrogen bonding into a 3 dimensional shape. Water has about 11 or more known forms. This why water is a liquid whereas the much heavier hydrogen sulphide is a gas (no hydrogen bonding)
One mole of any gas will occupy 22.710 980 litres at 0°C, 24.789 598 at 25°C. So just 18g of water in it's monomolecular gaseous state will occupy approx 22.7 litres about 40 pints or 5 UK gallons. Alternatively one pint of water 568 g, is 31.55 moles occupying 716.3 litres or 1260 pints. 157.6 UK gallons as a gas.
What is the molecular mass of sodium sulphate?
- The chemical form of sodium sulfate is Na2SO4
- Atomic masses of Na, S, and O are respectively 22.98977, 15.99944. and 32.06512
- Accordingly,the molecular mass M is: M =22.98977x2+32.06512+15.99944x4 or M = 142.042
- Sodium sulfate is chemically very stable, being unreactive toward most oxidising or reducing agents at normal temperatures.
How many moles of urea 60.0 g mol must be dissolved in 100.0g of water to give a 2.5 molal solution?
The answer is 15,015 g.
How many grams are in 6.60 moles of ZnO?
You need the molar solution to get the number of moles present in 6.52g of Zinc Sulfate.
Look at your atomic masses for phosphorus and oxygen. Set up 2.5/31 and 3.23/16. This makes 0.08 and 0.2. Now consider 0.08/0.2 to equal 0.4. So, your ratio of P to O is 0.4, which is 4/10. So, your formula, which reflects that ratio, is P4O10. That's tetraphosphorus decoxide, a molecular solid used in match-heads.
What mass is the of 4.52 x 10-3 moles of C20H42?
There are two types and many other isomers of C20H42
(wikipedia citation "It has 366,319"; all of them have different physical properties)
1.
n-Icosane (alternative spelling eicosane) Density of the UNbranched n-icosane: 932 mg mL−1 (at 20 °C)
Molecular formula CH3(CH2)18CH3
2. IUPAC name: 2,6,10,14-Tetramethylhexadecane. Density 791 mg mL−1 (at 20 °C).
Molecular formula: CH3CH(CH3)CH2CH2-(CH2CH(CH3)CH2CH2)-(CH2CH(CH3)CH2CH2)-CH2CH(CH3)CH2CH3
Molarity, abbrev. M, units: mol/L, mmol/ml
What is the number of moles of gas in 56.0 L of oxygen at STP?
4 g of Helium = 1 mole.So, 56 g of helium = 14 moles
How many moles are in 34.2 grams of aluminum?
The number of grams of Aluminum in one mole of Aluminum is the number under the element's symbol, on the periodic table of the elements, which is 26.981. With compounds, water, for example, is an oxygen and two hydrogens. So you would add 15.999 to 2(1.0079). You multiply the hydrogen's number by two because there's two of them.
How many moles of water are produce when 45.3 moles of hydrogen reacts with oxygen?
Since hydrogen is a gas, we would need more information to answer it. As chance wrote, you will need twice as much hydrogen as oxygen. However, in order to know what the volume of that hydrogen is, we also need to know the temperature and pressure so that we can use the universal gas law to get the answer.
How many moles of aluminum are in 10.8 grams?
Well, one mole is 26.98 g, right? Your ten grams is thus (10/26.98) moles.
How many moles are in 45g of F?
The molecular mass of fluorine gas, F2 is 2(19.0) = 38.0Amount of F2 = mass of sample/molar mass = 9.5/38.0 = 0.25mol
There are 0.25 moles of fluorine in a 9.5g pure sample.
This is the number before a chemical compound.
How many moles of Fe are present in 30 grams in rust?
This amount may be different because rust is not a clearly definite compound.
How many moles of CO are produced when 2.1moles C reacts?
The reaction is:
2 C + O2 = 2 CO
So 2,1 moles are obtained.
