Chemistry, 30.07.2019 19:30 Itasouu

How many molecules of cacl2 are equivalent to 75.9 g cacl2

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Answer from: jadenp23

First, you need to find:
One mole of $CaCl_{2}$ is equivalent to how many grams?

Well, for this you have to look up the periodic table. According to the periodic table:
The atomic mass of Calcium Ca = 40.078 g (See in group 2)
The atomic mass of Chlorine Cl = 35.45 g (See in group 17)

As there are two atoms of Chlorine present in $CaCl_{2}$ , therefore, the atomic mass of $CaCl_{2}$ would be:

Atomic mass of $CaCl_{2}$ = Atomic mass of Ca + 2 * Atomic mass of Cl

Atomic mass of $CaCl_{2}$ = 40.078 + 2 * 35.45 = 110.978 g

Now,

110.978 g of $CaCl_{2}$ = 1 mole.
75.9 g of $CaCl_{2}$ = $\frac{75.9}{110.978} moles$ = 0.6839 moles.

Hence,
The total number of moles in 75.9g of $CaCl_{2}$ = 0.6839 moles

According to Avogadro's number,
1 mole = 1 * $6.022 * 10^{23}$ molecules
0.6839 moles = 0.6839 * $6.022 * 10^{23}$ molecules = $4.118*10^{23}$ molecules

Ans: Number of molecules in 75.9g of $CaCl_{2}$ = $4.118*10^{23}$ molecules

-i

Answer from: yangyang7

4.11 * 10^ 23 molecules

Explanation:

1) Data:

Compound: CaCl2

mass, m = 75.9 g

unknown, N = ?

2) Formulas:

N = n * Avogadro's number = n * 6.022 * 10^23 molecules / mol

n = mass in grams / molar mass

molar mass = sum of the masses of the atoms in the molecular formula

3) Solution

molar mass of CaCl2:

      mass of Ca = 1 * atomic mass of Ca = 40.1 g/mol
      mass of Cl2 = 2 * atomic mass of Cl2 = 2 * 35.5 g/mol = 71.0 g/mol
      molar mass = 40.1 g/mol + 71.0 g/mol = 111.1 g/mol

n = m / molar mass = 75.9 g / 111.1 g/mol = 0.683 mol

N = n * 6.022 * 10^23 = 0.683 mol * 6.022 * 10^23 molecules / mol = 4.11 * 10^23 molecules, which is the answer.

Answer from: Quest

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –

6.022

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,

will have a gram-molecular weight of 352g.

Answer from: Quest

Afraidsugar lol it’s the third one

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