what is the gram formula mass of li2so4

Answer 1

Li₂SO₄ has 2 Li, 1 S, and 4 O's. To find the gram formula mass, you have to find the g/mol.

Basic process is # of each atom x its molar mass off of the periodic table. Then add up the masses. Li has 6.94 g/mol, S has 32.06 g/mol, and O has 16.0 g/mol.

So,

Li 2 x 6.94 = 13.88 g/mol

S 1 x 32.06 = 32.06 g/mol

O. 4 x 16.0 = 64.0 g/mol

Get the total: 13.88 + 32.06 + 64.0 = 109.94 g/mol. If you were going to 3 sig figs, this would give 110 g/mol which means 1 mol of Li₂SO₄ will have 110 g if you mass it on a triple beam balance (or other scale).

The gram formula mass is often called the molar mass, molecular mass, g/mol. They all mean essentially the same thing. A formula is an ionic compound. A molecule is a covalent compound. The molar mass of a ionic compound is therefore called the gram formula mass. The molar mass of a covalent compound is therefore called a molecular mass. The units for molar mass are g/mol, so you should be able to see how the words are interchangeable, and all describe the same process, just they can give you a little more specific information by using molecular or gram formula mass instead of molar mass.

A molar mass has the same numeric value as an atomic mass, but an atomic mass uses the units AMU or u. Amu are so small, they can't be measured reliably in a lab, so we use 12 g of C-12 as our basis for a bigger unit, the mole (abbreviated mol), so that we can then convert amu into grams (which CAN be measured in a lab). So, C-12 has 12 amu as its atomic mass (6 protons & 6 neutrons--each with 1 amu mass & 6 electrons with almost no mass), and C-12 has 12 g/mol as its molar mass (6.02 x 10²³ x 6 protons, and 6.02 x 10²³ neutrons to give 12 grams in 1 mole). NOTE: the masses listed on the periodic table are average masses for each element based on an element's isotopes, which is why they have decimal numbers and go to different levels of precision (decimal places). Avg. mass = % isotope A x mass isotope A + % isotope B x mass isotope B + % isotope C x mass isotope C + .....

Answer 2

You as for the "gram formula" of Li2SO4

In Chemistry you will hear this called the molar mass

This should lead you directly to the periodic table

On the periodic table look for Li

The top of the elemental box is the periodic number

The middle is the symbol for that element, i.e. Li with the full spelling usually underneath

The bottom has the molar mass or the number of grams/mol in 1 of those elements

we have 2 Li elements in this case, Lithium is Li and is #3 on the periodic table of elements, the molar mass of 1 element is 6.94 but we have 2 in this case (Li2) so we need to account for that:

Li2 = 2*(6.94) = 13.88

S = Sulfur, element #16, molar mass 32.06 and we have one so it is just 32.06

O = Oxygen, element #8, molar mass 15.999 for 1 element, we have 4:

O4 = 4*(15.999)= 63.996

To get our compound we add all our elements together

Li2SO4

Li2 + S + O4 = 13.88 + 32.06 + 63.996 = 109.94 molar mass of Li2SO4