Question

calculate number of molecules in 85 grams of CH4 ( atomic mass of carbon =12 , atomic mass of hydrogen =1)​

Answer 1

31.99 × 10²³

Explanation:

molar mass of CH₄ = 16 g

Molar mass of an atom has the number of molecules = Avagadro's number

                                                                                             (6.022 × 10²³)

16 g of CH₄ has 6.022 × 10²³ number of molecules

85 g of CH₄ will have x number of molecules

x = 6.022 × 10²³ × 85/ 16

x = 31.99 × 10²³

Hence 85 g of methane will have 31.99 × 10²³ number of molecules in it.

Answer 2

Answer:

The number of molecules in 85 g of $CH_{4}$ is $31.98*10^{23}$.

Explanation:

Given mass of $CH_{4}$ = 85 g

Given that:

Atomic mass of carbon = 12 g/mol

Atomic mass of hydrogen = 1 g/mol

Molar mass of $CH_{4}$ = (12×1) + (1×4) = 16 g/mol

Number of moles = given mass ÷ molar mass

                             = $\frac{85}{16}$ = 5.31 moles

1 mole of $CH_{4}$ contains $6.022*10^{23}$ molecules

∴5.31 moles of $CH_{4}$ contain $6.022*10^{23} *5.31$ molecules

                                              = $31.98*10^{23}$ molecules