Chemical Calculation 1

Which of the following statements regarding the mole is INCORRECT?

• A mole is a unit of quantity equal to 6.02 x 10²³ particles.

• The number of particles in a mole is known as Avogadro’s number.

• 1 mole of O₂ molecules means there are 6.02 x 10²³ O₂ molecules

• 1 mole of O₂ molecules means there are 6.02 x 10²³ O atoms of oxygen

The mass of one mole of an element is equal to

• its atomic number from the periodic table, but in amus.

• its atomic mass from the periodic table, but in kilograms

• its atomic mass from the periodic table, but in grams.

• its atomic number from the periodic table, but in grams.

What is the molar mass of PbSO₄?

• 303 g/mol

• 255 g/mol

• 163 g/mol

• 372 g/mol

Determine the mass of 4.20 moles of C₆H₁₂

• 352.8 g

• 0.0499 g

• 337 g

• 2.53 x 10²⁴ g

Calculate the number of atoms in 0.0340 g Zn. [A_r of Zn is 65]

Help: You need to find how many mole of Zn there are first.

• 5.20 x 10^-4 atoms Zn

• 3.13 x 10²³ atoms Zn

• 3.15 x 10²⁰ atoms Zn

• 2.05 x 10²² atoms Zn

How many grams are in 1.2 moles of neon?

• 0.059 grams

• 7.2 x 10²³ grams

• 2.0 x 10^-24 grams

• 24 grams

What is the molar mass of table salt (NaCl)? Read all options! Be careful!

• 58.44 amu

• 35.45 g/mol

• 22.99 g/mol

• 58.5 g/mol

To melt the ice, Juan throws 455 g of calcium chloride, CaCl₂ on his sidewalk. How many moles of CaCl₂ did he throw?

• 50,500 moles

• 4.10 moles

• 7.56 x 10^-22 moles

• 111 moles

How many atoms are contained in 25 g of NaBr? (Atomic mass of Na = 23, Br = 80)

• 102.96 atoms

• 2.92 x 10²³ atoms

• 1.46 x 10²³ atoms

Identify the number of Chlorine atoms in 65.8 g CaCl_2.

• 7.14 x 10²³ atoms

• 8.71 x 10²³ atoms

• 1.22 x 10²³ atoms

• 3.57 x 10²³ atoms