4. How many moles of gold (Au) are in a pure gold nugget having a mass of 25.0 grams.

0.127 mol Au

Math

Order of Operations: BPEMDAS

Chemistry

Atomic Structure

Stoichiometry

Step 1: Define

[Given] 25.0 g Au

[Solve] moles Au

Step 2: Identify Conversions

[PT] Molar Mass of Au - 196.97 g/mol

Step 3: Convert

Step 4: Check

Follow sig fig rules and round. We are given 3 sig figs.

0.126923 mol Au ≈ 0.127 mol Au

Explanation:

To convert from mass to moles, the molar mass must be used. This can be found on the Periodic Table.

Use this number as a ratio.

Multiply by the given number of grams.

Flip the fraction so the grams of gold will cancel.

The original measurement has 3 significant figures, so the answer must have the same. For the number we calculated that is the thousandth place. The 9 in the ten thousandth place tells us to round the 6 to a 7.

25.0 grams of gold is about 0.127 moles of gold.

2b2t

explanation:

2b2t