Mole-atom conversions
1. how many moles are 1.55 x 1027 atoms of zinc (zn)?

2. how many atoms are in 25.0 moles of calcium (ca)?

3. how many atoms are in 0.35 moles of carbon (c)?

4. how many moles are 7.6 x 1024 atoms of helium?

mole-mass conversions
how many moles in 28.o grams of oxygen?

what is the mass of 5.0 moles of iron?

find the number of moles of argon in 452 g of argon.

find the grams in 16.5 mol of hydrogen.

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Explanation:

1) How many moles are 1.55 × 10²⁷ atoms of zinc?

0.26 × 10⁴ mole

Explanation:

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

For example,

18 g of water = 1 mole = 6.022 × 10²³ molecules of water

1.008 g of hydrogen = 1 mole = 6.022 × 10²³ atoms of hydrogen

For  1.55 × 10²⁷ atoms of zinc:

1.55 × 10²⁷ atoms  × 1 mole/ 6.022 × 10²³ atoms

0.26 × 10⁴ mole

2) How many atoms are in 25.0 moles of calcium?

150.55  × 10²³ atoms.

Explanation:

According to Avogadro number,

one mole of substance = 6.022 × 10²³ atoms

The number 6.022 × 10²³ is called Avogadro number.

For 25.0 moles of calcium:

one mole of calcium = 6.022 × 10²³ atoms

25.0 mole × 6.022 × 10²³ atoms /1 mole

150.55  × 10²³ atoms.

So 25.0 moles of calcium contain 150.55  × 10²³ atoms.

3) = How many atoms are in 0.35 moles of carbon?

2.12× 10²³ atoms.

Explanation:

According to Avogadro number,

one mole of substance = 6.022 × 10²³ atoms

The number 6.022 × 10²³ is called Avogadro number.

For 0.35 moles of carbon:

one mole of carbon = 6.022 × 10²³ atoms

0.35 mole × 6.022 × 10²³ atoms /1 mole

2.12× 10²³ atoms.

So 0.35 moles of carbon contain 2.12× 10²³ atoms.

4 ) How many moles are 7.6 × 10²⁴ atoms of hellium?

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

The number 6.022 × 10²³ is called Avogadro number.

For example,

18 g of water = 1 mole = 6.022 × 10²³ molecules of water

1.008 g of hydrogen = 1 mole = 6.022 × 10²³ atoms of hydrogen

For  7.6 × 10²⁴ atoms of hellium:

7.6 × 10²⁴ atoms × 1 mole/ 6.022 × 10²³ atoms

12. 6  mole

Mass - Mole conversion:

How many moles in 28.0 gram of oxygen?

1.75 mol

Explanation:

Given data:

Mass of oxygen = 28 g

Number of moles = ?

Solution:

Formula:

Number of moles = mass/ molar mass

Molar mass of oxygen = 16 g/mol

Now we will put the values in formula:

Number of moles = 28 g / 16 g/mol

Number of moles = 1.75 mol

So 28 g of oxygen contain 1.75 moles.

3)  Find the number of moles of argon in 452 g?

11.31 mol

Explanation:

Given data:

Mass of argon = 452 g

Number of moles = ?

Solution:

Formula:

Number of moles = mass/ molar mass

Molar mass of argon= 39.95 g/mol

Now we will put the values in formula:

Number of moles =  452 g /39.95 g/mol

Number of moles = 11.31 mol

So 452 g of argon contain 11.31 moles.

2) What is the mass of 5.0 moles of iron?

Mass = 279.25 g

Explanation:

Given data:

Mass of iron = ?

Number of moles of iron = 5.0 mol

Solution:

Formula:

Mass = number of moles × molar mass

Molar mass of iron = 55.85 g/mol

Now we will put the values in formula:

Mass = number of moles × molar mass

Mass = 5 mol ×  55.85 g/mol

Mass = 279.25 g

4) Find the grams of 16.5 mole of hydrogen?

Mass = 16.632 g

Explanation:

Given data:

Mass of hydrogen = ?

Number of moles of hydrogen = 16.5 mol

Solution:

Formula:

Mass = number of moles × molar mass

Molar mass of hydrogen = 1.008 g/mol

Now we will put the values in formula:

Mass = number of moles × molar mass

Mass = 16.5 ×  1.008 g/mol

Mass = 16.632 g

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.

the answer is   c.) 1575 j.

explanation: