Question

40 POINTS! WILL MARK BRAINLIEST!! Determine the mass in grams of 4.83 × 10²¹ atoms of arsenic. (The mass of one mole of arsenic is 74.92 g.)

Answer 1

Answer:

$\boxed {\boxed {\sf 0.601 \ g \ As}}$

Explanation:

We want to convert atoms of arsenic to mass in grams. We have to complete 3 steps.

1. Convert Atoms to Moles

The first step is converting atoms to moles. We use Avogadro's Number for this. This number is 6.022*10²³ and it is the number of representative units (molecules, atoms, etc.) in 1 mole of a substance. In this problem, the particles are atoms of arsenic. So, 1 mole of arsenic contains  6.022*10²³ atoms of arsenic. Use this information to make a ratio.

$\frac{1 \ mol \ As}{{6.022*10^{23} \ atoms \ As} }$

Multiply by the number of atoms provided in the problem: 4.83 × 10²¹

$4.83 *10^{21} \ atoms \ As *\frac{1 \ mol \ As}{{6.022*10^{23} \ atoms \ As} }$

The units of atoms of arsenic (atoms As) cancel.

$4.83 *10^{21} *\frac{1 \ mol \ As}{{6.022*10^{23}} }$

Condense into 1 fraction.

$\frac{4.83 *10^{21} }{{6.022*10^{23}} } \ mol \ As$

$0.008020591166 \ mol \ As$

2. Convert Moles to Grams

The next step is converting moles to grams. We use the molar mass for this, which is provided. There are 74.92 grams of arsenic in 1 mole of arsenic, so we can make another ratio.

$\frac {74.92 \ g\ As}{ 1 \ mol \ As}$

Multiply by the number of moles we calculated.

$0.008020591166 \ mol \ As*\frac {74.92 \ g\ As}{ 1 \ mol \ As}$

The units of moles of arsenic (mol As) cancel.

$0.008020591166 *\frac {74.92 \ g\ As}{ 1}$

$0.6009026901 \ g \ As$

3. Round

The original measurement of atoms (4.83 × 10²¹ ) has 3 significant figures, so our answer must have the same.

For the number we calculated, that is the thousandth place. The 9 in the ten-thousandth place (0.6009026901) tells us to round the 0 to a 1.

$0.601 \ g \ As$

There are approximately 0.601 grams of arsenic.