Question

What is the mass of 1.56 x 1021 atoms of magnesium in grams? a) 4.72 x 10-5 b) 0.0630 c) 0.142 d) 1.07 x 10-4 e) none of the above

Answer 1

The mass of 1.56 x 10^21 atoms of magnesium is calculated by determining the number of moles and then converting that to grams using the molar mass of magnesium, resulting in 0.0630 grams.

Step-by-step explanation:

To find the mass of 1.56 x 1021 atoms of magnesium, we need to use the concept of the molar mass and Avogadro's number, which is 6.022 x 1023 atoms/mol. Magnesium's molar mass is approximately 24.305 grams per mole.

First, we calculate the number of moles of magnesium atoms:

1. Number of moles = Number of atoms / Avogadro's number
2. Number of moles = 1.56 x 1021 atoms / 6.022 x 1023 atoms/mol
3. Number of moles = 2.59 x 10-3 moles

Now, we convert moles to grams using the molar mass:

1. Mass = Number of moles x Molar mass
2. Mass = 2.59 x 10-3 moles x 24.305 g/mol
3. Mass = 0.0629 grams, or 0.0630 grams when rounded to four significant figures

Therefore, the correct answer is (b) 0.0630 grams.

Answer 2

The mass of 1.56 x 10²¹atoms of magnesium is 0.0630 grams.

Step-by-step explanation:

To find the mass of 1.56 x 10²¹ atoms of magnesium, we need to multiply the number of atoms by the molar mass of magnesium. The molar mass of magnesium is 24.31 grams per mole. So, the mass of 1.56 x 10²¹ atoms of magnesium is:

1.56 x 10²¹ atoms * (24.31 g/mol / 6.022 x 1023 atoms/mol) = 0.0630 grams

Therefore, the correct answer is b) 0.0630.