Question

calculate the number of moles in a) 1.11 gram of calcium chloride
b) 1.5 into 10^30 molecules of ammonia​

Answer 1

Answer:

a) 0.01

Explanation:

To calculate no. of moles, we use:-

$no \: of \: moles \: = \frac{given \: mass}{molar \: mass}$

______________________________________________

a) 1.11g of calcium chloride

Given mass= 1.11g

molar mass=

$no. \: of \: mass = \: \frac{given \: mass}{molar \: mass}$

$= \frac{111}{111 \times 100} = \frac{1}{100} = 0.01$

_________________________________________________

Answer 2

Answer:

a) The number of moles in 1.11 gram calcium chloride is 0.01 mol.

b) The number of moles in 1.5 × 10³⁰ molecules of ammonia is 25 × 10⁵ mol ( Approx. ).

Explanation:

a)

We have to calculate the number of moles of 1.11 gram of calcium chloride.

Now, we know that,

Molecular formula of calcium chloride = CaCl₂

∴ Molar mass of calcium chloride = [ ( 1 × Atomic mass of calcium ) + ( 2 × Atomic mass of chlorine ) ]

⇒ Molar mass of calcium chloride = [ ( 1 × 40 ) + ( 2 × 35.5 ) ]

⇒ Molar mass of calcium chloride = ( 40 + 71 )

⇒ Molar mass of calcium chloride = 111 g mol¯¹

Now, we know that,

Number of moles of calcium chloride = ( Mass of calcium chloride ) / ( Molar mass of calcium chloride )

⇒ Number of moles of calcium chloride = 1.11 g / 111 g mol¯¹

⇒ Number of moles of calcium chloride = 1.11 ÷ 111 mol

⇒ Number of moles of calcium chloride = 0.01 mol

∴ The number of moles in 1.11 gram calcium chloride is 0.01 mol.

─────────────────────────

b)

We have to calculate the number of moles in 1.5 × 10³⁰ molecules of ammonia.

Now, we know that,

Number of molecules = Number of moles × Avogadro's number

⇒ Number of molecules = n × Nᴀ

⇒ 1.5 × 10³⁰ = n × 6.022 × 10²³

⇒ n = ( 1.5 × 10³⁰ ) / ( 6.022 × 10²³ )

⇒ n = ( 1.5 ÷ 6.022 ) × ( 10³⁰ ÷ 10²³ )

⇒ n = 0.249 × 10³⁰ ⁻ ²³

⇒ n = 0.249 × 10⁷

⇒ n ≈ 0.25 × 10⁷

⇒ n ≈ 25 × 10⁵ mol

∴ The number of moles in 1.5 × 10³⁰ molecules of ammonia is 25 × 10⁵ mol ( Approx. ).