Question

How many atoms of Ca are present in 80.156 grams of Ca? (4 points) 1.2044 × 1024 2.4088 × 1024 4.8270 × 1025 1.9346 × 1027

Answer 1

Answer: 1.2044 × 10^24

Explanation:

1 mole of calcium is 40 gram

Based on Avogadro's law:

1 mole of any substance has 6.02 x 10^23 atoms, also 1 mole of calcium is 40gram

So, 1 mole of calcium = 6.02 x 10^23 atoms

Also, 1 mole of calcium is 40gram

40 grams of calcium = 6.02 x 10^23 atoms

80.156 grams of calcium = Z atoms

To get the value of Z, cross multiply:

Z atoms x 40 grams = 6.02 x 10^23 atoms x 80.156 grams

40Z = 482.54 x 10^23

Z = (482.54 x 10^23/40)

Z = 12.06 x 10^23

Put result in standard form

Z = 1.206 x 10^24 atoms

Thus, 1.206 x 10^24 atoms of Ca are present in 80.156 grams of Ca

Answer 2

Answer:

1.204x10^24atoms

Explanation:

From Avogadro's hypothesis, 1mole of any substance contains 6.02x10^23 atoms.

This implies that 1mole of Ca also contains 6.02x10^23 atoms.

1 mole of Ca = 40.078g

Now, if 40.078g of Ca contains 6.02x10^23 atoms,

then 80.156g of Ca will contain = (80.156 x 6.02x10^23)/40.078 = 1.204x10^24atoms

Therefore, 80.156g of Ca contains 1.204x10^24 atoms