Calculating Molecular Weights and Formulas

Calculating Molecular Weights and Formulas

Assessment

Interactive Video

Chemistry

9th - 10th Grade

Practice Problem

Hard

Created by

Lucas Foster

FREE Resource

The video tutorial explains how to calculate the molecular weight or molar mass of lead(II) nitrate, Pb(NO3)2. It begins by identifying the atomic weights of lead, nitrogen, and oxygen from the periodic table. The tutorial then demonstrates how to apply the subscripts in the chemical formula to calculate the total molar mass, emphasizing the importance of correctly using parentheses and brackets to account for multiple atoms. The final calculation is presented, and the video concludes with a summary of the process.

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9 questions

Show all answers

1.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What is the atomic weight of lead (Pb) as mentioned in the video?

207.2 g/mol

27.2 g/mol

14.0 g/mol

16.0 g/mol

2.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

How is the atomic weight of nitrogen (N) rounded for calculation?

14.01

14.0

15.0

16.0

3.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What is the rounded atomic weight of oxygen (O) used in the calculation?

17.0

14.0

16.0

15.999

4.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

In the formula Pb(NO3)2, to which element does the subscript '3' apply?

Oxygen (O)

Nitrogen (N)

Lead (Pb)

The entire nitrate group

5.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What is the purpose of the brackets in the formula Pb(NO3)2?

To separate lead from nitrate

To apply the subscript 2 to the entire nitrate group

To denote a chemical reaction

To indicate multiplication by 3

6.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What is the result of multiplying 16.0 by 3 in the calculation?

33.2 g/mol

48.0 g/mol

62.0 g/mol

207.2 g/mol

7.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

What is the final molecular weight of lead(II) nitrate (Pb(NO3)2) as calculated in the video?

207.2 g/mol

33.2 g/mol

331.2 g/mol

62.0 g/mol

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