Chemistry - Conversions & Percent Composition

A sample of calcium carbonate (CaCO₃) weighs 50 grams. How many moles of CaCO₃ are in this sample? (Molar mass of CaCO₃ = 100.09 g/mol)

• 0.5 moles

• 1 mole

• 2 moles

• 0.25 moles

Tags

NGSS.HS-PS1-7

How many molecules are in 2.5 moles of carbon dioxide (CO₂)?

• 1.51 x 10²⁴ molecules

• 3.01 x 10²³ molecules

• 6.02 x 10²³ molecules

• 2.5 x 10²⁴ molecules

Tags

NGSS.HS-PS1-7

A compound is found to contain 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is the empirical formula of the compound?

• CH2O

• C2H4O2

• CH3O

• C3H6O3

A sample of a compound contains 4.8 grams of carbon, 0.8 grams of hydrogen, and 9.6 grams of oxygen. What is the empirical formula of this compound?

• CH2O

• C2H4O2

• CH3O

• C3H6O3

A compound consists of 3.5 grams of nitrogen and 14.0 grams of oxygen. What is the empirical formula of the compound?

• NO2

• N2O4

• NO

• N2O

Tags

NGSS.HS-PS1-7

How many moles are in 25 grams of sodium chloride (NaCl)?

• 0.428 moles

• 0.500 moles

• 0.600 moles

• 0.700 moles

Tags

NGSS.HS-PS1-7

How many molecules are in 2.5 moles of carbon dioxide (CO₂)?

• 1.505 x 10²⁴ molecules

• 1.000 x 10²⁴ molecules

• 2.000 x 10²⁴ molecules

• 3.000 x 10²⁴ molecules

Tags

NGSS.HS-PS1-7

How many molecules are in 3.0 moles of hydrogen gas (H₂)?

• 1.8066 x 10²⁴ molecules

• 2.0000 x 10²⁴ molecules

• 3.0000 x 10²⁴ molecules

• 4.0000 x 10²⁴ molecules

A compound consists of 4.4 grams of nitrogen and 12.6 grams of oxygen. What is the empirical formula of the compound?

• NO

• NO2

• N2O5

• N2O

Fill in the blank: A compound with 4.4 grams of nitrogen and 12.6 grams of oxygen has an empirical formula of ____.

• A) NO

• B) NO2

• C) N2O5

• D) N2O

Tags

NGSS.HS-PS1-7