1:28 Archives - TutorMyself Chemistry

1:28 understand how to carry out calculations involving amount of substance, relative atomic mass (Aᵣ) and relative formula mass (Mᵣ)

The following formula allows for the interconversion between a mass in grams and a number of moles for a given substance:

$Amount(mol) = \frac{mass(g)}{M_r}$

Example 1:

Calculate the amount, in moles, of 8.8 g of carbon dioxide (CO₂).

Step 1: Calculate the relative formula mass (M_r) of carbon dioxide (CO₂).

$Carbon\,dioxide = CO_2$

$Atoms\,present = (1 \times C) + (2 \times O)$

$M_r = (1 \times 12) + (2 \times 16) = 44$

Step 2: Use the formula to calculate the amount in moles.

$Amount = \frac{mass(g)}{M_r}$

$Amount = \frac{8.8}{44}$

$Amount = 0.2 mol$

Example 2:

Calculate the mass of 2 mol of copper(II) sulfate (CuSO₄).

Step 1: Calculate the relative formula mass (M_r) of copper(II) sulfate (CuSO₄).

$copper(II)\,sulfate = CuSO_4$

$Atoms\,present = (1 \times Cu) + (1 \times S) + (4 \times O)$

$M_r = (1 \times 63.5) + (1 \times 32) + (4 \times 16) = 159.5$

Step 2: Rearrange the formula to calculate the mass.

$mass = amount \times M_r$

$mass = 2 \times 159.5$

$mass = 319g$

Spec	Q'stion	Ans	MS
1:28	Jan '13 (2), Q 7 a iii	Answer	MkS
1:28	Jan '13 (2), Q 7 a iv	Answer	MkS
1:28	Jan '14 (1), Q 12 a i	Answer	MkS
1:28	Jan '14 (1), Q 12 b	Answer	MkS
1:28	Jan '15 (1), Q 11 d ii	Answer	MkS
1:28	Jan '15 (1), Q 11 d iii	Answer	MkS
1:28	Jan '15 (2), Q 7 b	Answer	MkS
1:28	Jan '16 (1), Q 12 a i	Answer	MkS
1:28	Jan '16 (1), Q 15 b ii	Answer	MkS
1:28	Jan '16 (1), Q 15 b iii	Answer	MkS
1:28	Jan '16 (2), Q 5 c i	Answer	MkS
1:28	Jan '16 (2), Q 6 c ii	Answer	MkS
1:28	Jan '17 (1), Q 5 c i	Answer	MkS
1:28	Jan '17 (1), Q 9 a i	Answer	MkS
1:28	Jan '17 (2), Q 6 c i	Answer	MkS
1:28	Jan '17 (2), Q 7 a i	Answer	MkS
1:28	Jan '18 (1), Q 13 a	Answer	MkS
1:28	Jan '18 (2), Q 5 c i	Answer	MkS
1:28	May '13 (1), Q 10 d i	Answer	MkS
1:28	May '13 (1), Q 10 d ii	Answer	MkS
1:28	May '13 (1), Q 10 d iii	Answer	MkS
1:28	May '14 (1), Q 15 a i	Answer	MkS
1:28	May '14 (1), Q 15 c i	Answer	MkS
1:28	May '14 (1R), Q 10 c i	Answer	MkS
1:28	May '14 (1R), Q 10 c ii	Answer	MkS
1:28	May '14 (1R), Q 10 c iii	Answer	MkS
1:28	May '14 (1R), Q 10 c iv	Answer	MkS
1:28	May '14 (2), Q 7 c i	Answer	MkS
1:28	May '14 (2), Q 7 c ii	Answer	MkS
1:28	May '14 (2R), Q 5 b i	Answer	MkS
1:28	May '15 (1), Q 11 e	Answer	MkS
1:28	May '15 (1), Q 8 f ii	Answer	MkS
1:28	May '15 (2), Q 5 b ii	Answer	MkS
1:28	May '15 (2), Q 6 c ii	Answer	MkS
1:28	May '16 (1), Q 14 a	Answer	MkS
1:28	May '16 (1), Q 14 b	Answer	MkS
1:28	May '16 (1), Q 8 c	Answer	MkS
1:28	May '16 (1R), Q 11 e	Answer	MkS
1:28	May '16 (2), Q 3 c	Answer	MkS
1:28	May '16 (2), Q 8 a	Answer	MkS
1:28	May '17 (1R), Q 15 a	Answer	MkS
1:28	May '17 (2R), Q 8 a i	Answer	MkS

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