How would you calculate the moles in a mass of a substance?

Answer 1

molarity equals the number of moles divided by the number of liters. unit is molarity, or the solution is ___ molar. the blank is the numeric you get by the division of the moles by liters. I was taught to use dimensional analysis. A mole is 6.02 * 10^23 and you just have to get the unit from liters or whatever you started with to that. I'm sure if you type dimensional analysis into Google it will tell you how to do it because I can't really help you much more without knowing the problem and the units it started in. More simply, you could multiply the concentration by the volume to find the number of moles. e.g. 0.1mol^dm-3 x 0.5L = 0.05M

Answer 2

Use the Molar MassTo find the mass of one mole of any substance, you need the molar mass, which is found by using the Periodic Table. If the substance is a pure element, just read the number directly off the table for that element (if you use the periodic table with the link to the left of this answer, it is the number written directly below the symbol for that element). If the substance is a compound, you must add up the molar mass of each element found in the compound to give the total molar mass of the substance.

For example, how do you find out the mass of 1 mole of substance. Let's take magnesium as an example: How much does one mole of magnesium metal weigh?

The molar mass of magnesium (Mg) is found on the periodic table. The molar mass is how much one mole of an element weighs.

In this case, the molar mass of Mg is 24.31 g/mole.

So 1 mole of Mg weighs exactly 24.31 grams.

Another example: What if the question is asked the other way around. Instead you have a certain mass of a chemical, and you want to know how many moles that is equal to. We'll use table salt, NaCl, as an example here. How many moles are there in 29.25 grams of salt (sodium chloride or NaCl)?

First, you need to find the molar mass of NaCl. To do that, just add up the masses of Na and Cl:

22.989 g/mol + 35.453 g/mol = 58.442 g/mol.

So 1 mole of table salt weights 58.442 grams. So if you have 29.25 grams, you just divide:

29.25 grams ÷ 58.442 g/mol = 0.500 moles of NaCl

See the link below to find a periodic table with this information.

Answer 3

grams of substance/ molar mass of substance.

sodium chloride: NaCl. The weight of one mole, rounded to the nearest tenth, is the atomic weight of sodium, 23g, plus the atomic weight of chorine, 35.5. Therefore one mole of solute would be 58.5g. Assuming for this example that there are 24g of NaCl, the conversion would be: 24/58.5=.41 moles of solute.

molarity is moles/liters

Answer 4

volume of a mole = the number of moles multiplied by the molar volume

Answer 5

Number of moles = concentration(M) x volume(L)

where M = moles per litre and L = Litres

Answer 6

The sum of the atomic weights of the elements contained in a compound.

Example: anhydrous calcium chloride (CaCl2)

1 atom of Ca + 2 atoms of Cl = 110,98 g