How many moles of atoms are in 8.1 × 10^5
g
Pb?
Answer in units of mol.

3900 mol Pb

General Formulas and Concepts:

Chemistry - Atomic Structure

Explanation:

Step 1: Define

8.1 × 10⁵ g Pb

Step 2: Identify Conversions

Molar Mass of Pb - 207.2 g/mol

Step 3: Convert

= 3909.27 mol Pb

Step 4: Check

We are given 2 sig figs. Follow sig fig rules and round.

3909.27 mol Pb ≈ 3900 mol Pb

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%