10.5 Formulas of Hydrates

What is the correct chemical formula for barium hydroxide octahydrate?

• Ba(OH)₂ . 8H₂O

• Ba(OH)₂ . H₂O

• 8Ba(OH)₂ . H₂O

• Ba . 8(OH)₂

Which word indicates that two water molecules are associated with a substance in a chemical compound?

• mono-

• di-

• tri-

• an-

A hydrate is a compound that has a specific number of water molecules bound to its atoms. How many water molecules are bound to the hydrate shown in the circle graph?

• 6

• 7

• 8

• 10

One application of chemicals that can absorb water to form hydrates is as water-absorbing ________.

• surfactants

• hydrators

• dessicants

• antiseptics

What is the best method for removing water from a hydrated compound?

• freezing

• filtration

• distillation

• heating

Name the following ionic compound: MgSO₄ · 7H₂O

• magnesium sulfate pentahydrate

• magnesium sulfide heptahydrate

• magnesium sulfate heptahydrate

• magnesium sulfate octahydrate

Magnesium pentahydrate 

• MgCO₃ · 5H₂O
• MgCO₃ · 4H₂O
• MgCO₃ · 6H₂O
• MgCO₃ · 1H₂O

A 15.67 g sample of a hydrate of magnesium carbonate was heated to drive off the water. The mass was reduced to 7.58 g. What is the formula of the hydrate?

• MgCO₃ · 5H₂O
• MgCO₃ · 4H₂O
• MgCO₃ · 6H₂O
• MgCO₃ · 1H₂O

Tags

NGSS.HS-PS1-7

A hydrate of magnesium chloride is present and the following data is collected:

mass of evaporating dish = 22.130 grams

mass of dish + hydrate = 25.290 grams

mass of dish and contents after heating = 23.491 grams

What is the mass of the anhydrous MgCl₂?

• 1.799 g

• 3.160 g

• 1.361 g

• 23.491 g

Tags

NGSS.HS-PS1-7

What is the empirical formula for the following:
32.40% sodium, 22.5% sulfur; 45.1 % oxygen, 37.75% water?

• Na₂SO₄H₆O₃
• Na₂SO_{4 .} 2H₂O
• Na₂SO_{4 .} 3H₂O
• Na₂SO_{4 .} (H₂O)₃

Tags

NGSS.HS-PS1-7