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How many moles of FeCI3 are present in 345.0 g FeCI3

1 Answer

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Answer:


\boxed {\boxed {\sf About \ 2.127 \ moles \ of \ FeCl_3}}

Step-by-step explanation:

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

1. Find Molar Mass

The compound is iron (III) chloride: FeCl₃

First, find the molar masses of the individual elements in the compound: iron (Fe) and chlorine (Cl).

  • Fe: 55.84 g/mol
  • Cl: 35.45 g/mol

There are 3 atoms of chlorine, denoted by the subscript after Cl. Multiply the molar mass of chlorine by 3 and add iron's molar mass.

  • FeCl₃: 3(35.45 g/mol)+(55.84 g/mol)=162.19 g/mol

This number tells us the grams of FeCl₃ in 1 mole.

2. Calculate Moles

Use the number as a ratio.


(162.19 \ g \ FeCl_3)/(1 \ mol \ FeCl_3)

Multiply by the given number of grams, 345.0.


345.0 \ g \ FeCl_3 *(162.19 \ g \ FeCl_3)/(1 \ mol \ FeCl_3)

Flip the fraction so the grams of FeCl₃ will cancel.


345.0 \ g \ FeCl_3 *(1 \ mol \ FeCl_3)/(162.19 \ g \ FeCl_3)


345.0 *(1 \ mol \ FeCl_3)/(162.19 )


(345.0 \ mol \ FeCl_3)/(162.19 )

Divide.


2.12713484 \ mol \ FeCl_3

3. Round

The original measurement of grams, 345.0, has 4 significant figures. We must round our answer to 4 sig figs.

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

The 1 in the ten thousandth place tells us to leave the 7 in the thousandth place.


\approx 2.127 \ mol \ FeCl_3

There are about 2.127 moles of iron (III) chloride in 345.0 grams.

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