Question

12. How many grams are equal to 3.46 moles of sodium sulfide, Na2S?​ with work please

Answer 1

Mass = 269.8 g

Step-by-step explanation:

Given data:

Number of moles of Na₂S = 3.46 mol

Mass of Na₂S = ?

Solution:

Formula:

Mass = number of moles × molar mass

Molar mass of Na₂S = 78.0 g/mol

Mass = 3.46 mol × 78.0 g/mol

Mass = 269.8 g

Answer 2

`\boxed {\boxed {\sf About \ 270 \ grams \ of \ Na_2 S}}`

Step-by-step explanation:

To convert from moles to grams, the molar mass must be used.

1. Find Molar Mass

The compound is sodium sulfide: Na₂S

First, find the molar masses of the individual elements in the compound: sodium (Na) and sulfur (S).

• Na: 22.9897693 g/mol
• S: 32.07 g/mol

There are 2 atoms of sodium, denoted by the subscript after Na. Multiply the molar mass of sodium by 2 and add sulfur's molar mass.

• Na₂S: 2(22.9897693 g/mol)+(32.07 g/mol)=78.0495386 g/mol

This number tells us the grams of sodium sulfide in 1 mole.

2. Calculate Grams

Use the number as a ratio.

`(78.0495386 \ g \ Na_2S)/(1 \ mol \ Na_2S)`

Multiply by the given number of moles, 3.46.

`3.46 \ mol \ Na_2S *(78.0495386 \ g \ Na_2S)/(1 \ mol \ Na_2S)`

The moles of sodium sulfide will cancel.

`3.46 *(78.0495386 \ g \ Na_2S)/(1 )`

`3.46 *{78.0495386 \ g \ Na_2S}`

`270.051404 \ g \ Na_2 S`

3. Round

The original measurement of grams, 3.46, has 3 significant figures. We must round our answer to 3 sig figs.

For the answer we calculated, that is the ones place.

The 0 in the tenth place tells us to leave the 0 in the ones place.

`\approx 270 \ g \ Na_2 S`

There are about 270 grams of sodium sulfide in 3.46 moles.