5.45 grams of magnesium sulfate heptahydrate is how many moles?

5.45 g is 0.0221 moles of magnesium sulfate heptahydrate.

Explanation:

The molecular formula of magnesium sulfate heptahydrate is Mg SO₄·7H₂O.

The molar mass of this compound is calculated adding the molar mass of each element:

Mg: 24. 3 g

S: 32. 1 g

O: 16 g

H: 1 g

Then the mass of a mole of Mg SO₄·7H₂O is:

24.3 g + 32.1 g +4(16 g) + 7(2(1) + 16) = 246.4 g.

if 246.4 g is 1 mole of Mg SO₄·7H₂O, then 5.45 g will be:

5.45 g *(1 mol / 246.4 g) = 0.0221 mol.

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.