12) Naturally occurring argon is composed of 0.3365% of 36Ar (atomic mass, 35.9675 u), 0.0632% of 38Ar (atomic mass, 37.9627 u), and 99.6003% of 40Ar (atomic mass, 39.9624 u). Use these data to calculate the average atomic mass of argon.
(35.9675*0.003365) + (37.9627*0.000632) + (39.9624*0.99600) = ?
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a 21.0kg iron weightlifting plate has a volume of 2670 cm3 what is the density of the iron plate in g/cm3?
To calculate the average atomic mass of argon, we need to consider the mass and abundance of each isotope and then find their weighted average.
Step 1: Convert the percentages to decimal form.
The percentages given are 0.3365%, 0.0632%, and 99.6003%. To convert them to decimal form, divide each by 100.
0.3365% = 0.003365
0.0632% = 0.000632
99.6003% = 0.996003
Step 2: Multiply the abundance of each isotope by its atomic mass.
Multiply the decimal abundance of each isotope by its atomic mass.
For 36Ar:
Abundance (0.003365) × Atomic mass (35.9675 u) = 0.1204 u
For 38Ar:
Abundance (0.000632) × Atomic mass (37.9627 u) = 0.0240 u
For 40Ar:
Abundance (0.996003) × Atomic mass (39.9624 u) = 39.9138 u
Step 3: Add up the values obtained from step 2.
Add the values obtained for each isotope from step 2.
0.1204 u + 0.0240 u + 39.9138 u = 40.0582 u
Step 4: Round to the correct number of decimal places.
The average atomic mass should typically be reported to two decimal places.
Rounding 40.0582 u to two decimal places gives us 40.06 u.
Therefore, the average atomic mass of argon is approximately 40.06 u.