Unit 1.1 Chemistry

A compound contains 1.00 mol of Sb. 1.50 mol C and 4.50 mol of O What is the empirical formula?

• SbCO

• Sb₂C₃O₉

• SbC_1.5O_4.5

• SbC₃O₉

Tags

NGSS.HS-PS1-7

What is the molar mass of HgHCO₃

• 229.61 g/mol

• 287.65 g/mol

• 378.40 g/mol

• 261.6 g/mole

Which of the following nickle compounds contains the highest percentage nickle by mass?

• NiCl₂

• NiO₂

• NiO

• Ni₃(PO₄)₂

A compound has the empirical formula of PBr₅, it has a molecular formula mass of 431 g/mol. What is the molecular formula of this compound?

• P₂Br₁₀

• PBr₅

• P₃Br₁₅

• P₄Br₂₀

A 5.0g sample of MgCl₂ may contain measurable amounts of other compounds as impurities. Which of the following quantities is (are) needed to determine that the sample is pure MgCl₂?

• The color and density of the sample

• The mass of Mg in the sample only

• The number of moles of Cl in the sample only

• The mass of Mg and the mass of Cl in the sample

Tags

NGSS.HS-PS1-7

A sample of CaCO3 (molar mass 100. g) with additional impurities was reported as being 30. percent Ca. Assuming no calcium was present in the impurities, the percent of CaCO3 in the sample is

• 30%

• 40%

• 70%

• 75%

• 100%

According to the information in the table, a 1.00 g sample of which of the following contains the greatest mass of oxygen?

• Na₂O

• MgO

• K₂O

• CaO

Tags

NGSS.HS-PS1-7

To determine the percentage of water in a hydrated salt, a student heated a 1.2346 g sample of the salt for 30 minutes; when cooled to room temperature, the sample weighed 1.1857 g. After the sample was heated for an additional 10 minutes and again cooled to room temperature, the sample weighed 1.1632 g. Which of the following should the student do next?

• Use the smallest mass value to calculate the percentage of water in the hydrated salt.

• Repeat the experiment with a new sample of the same mass and average the results.

• Repeat the experiment with a new sample that has a different mass.

• Reheat the sample until its mass is constant.

• Use the average of the mass values obtained after the two heatings to calculate the percentage of water in the hydrated salt.

Tags

NGSS.HS-PS1-2

A student is given two 10g samples, each a mixture of only NaCl(s) and KCl(s) but in different proportions. Which of the following pieces of information could be used to determine which mixture has the higher proportion of KCl(s)?

• The volume of each mixture

• The mass of Cl in each mixture

• The number of isotopes of Na and K

• The reaction of each mixture with water

In 1.00 mol of potassium zirconium sulfate trihydrate, K₄Zr(SO₄)₄ • 3 H₂O, there are

• 3 × 6.02 × 10²³ hydrogen atoms

• 6.02 × 10²³ sulfur atoms

• 4 × 6.02 × 10²³ potassium atoms

• 4 moles of oxygen atoms

• 4 moles of zirconium atoms