How many moles are in 1.806 x 1024 molecules of bromine?

2.999 mol Br

Math

Pre-Algebra

Order of Operations: BPEMDAS

Chemistry

Atomic Structure

Step 1: Define

1.806 × 10²⁴ molecules Br

Step 2: Identify Conversions

Avogadro's Number

Step 3: Convert

= 2.999 mol Br

Step 4: Check

We are given 4 sig figs. Follow sig fig rules and round.

Our final answer is already in 4 sig figs, so there is no need to round.

Explanation:

To convert from moles to molecules, we must use Avogadro's Number.

This tells us the number of particles (atoms, molecules, ions, etc) in 1 mole. In this problem, the particles are molecules of bromine in 1 mole of bromine.

1. Convert from moles to molecules

Use Avogadro's number as a fraction or ratio.

Multiply this fraction by the given number of bromine molecules.

Flip the fraction so the molecules of bromine can cancel out.

Multiply and condense the expression into 1 fraction.

Divide.

2. Round

The original measurement, 1.806*10^24 has 4 significant figures (1, 8, 0, and 6). We must round our answer to 4 sig figs. For the answer we found, that is the thousandth place.

The 0 in the ten-thousandth place tels us to leave the 9 in the thousandth place.

There are about 2.999 moles of bromine in 2.806 *10^23 molecules.