Chemistry Midterm

How many grams of O2 gas can be produced by the decomposition of 25.0 grams of HgO? HgO = O2 + Hg

.0739 grams O2

120 grams of Al2(CrO4)3 = _____ moles

.30

Calculate the number of moles of xenon in 12.0 g of xenon.

0.0914 mol

An aluminum beverage can contains 12.0 fluid ounces of liquid. Express this volume in liters. (1 fl oz = 29.6 mL)

0.355 L

1.8 moles of SrI2 = _____ molecules

1.1 x 10^24

How many atoms are in 0.0728 g of PCl3?

1.28 x 10^21 atoms

An aluminum ion, Al^3+, has:

13 protons and 10 electrons

The density of ethanol is 0.798 g/mL. Calculate the mass of 17.4 mL of the liquid.

13.9 g/mL

What is the mass of 3.00 moles of ethanol, C2H6O?

138 g

A phosphide ion has:

15 protons and 18 electrons

What is the molar mass of acetaminophen, C8H9CO2?

151 g/mol

An atom of the isotope chlorine-37 consists of how many protons, neutrons, and electrons?

17 p, 20 n, 17 e

A piece of metal with a mass of 611 g is placed into a graduated cylinder that contains 25.1 mL of water, raising the water level to 56.7 mL. What is the density of the metal?

19.3 g/cm^3

How many grams are in 4.5 moles of sodium fluoride?

190 grams

What is the coefficient of H20 when the following equation is properly balanced with the smallest set of whole numbers? __ Na + __ H20 = __ NaOH + __ H2

2

The density of lead is 11.4 g/cm^3 at 25 degrees C. Calculate the volume occupied by 25.0 g of lead.

2.19 cm^3

An excess of sulfuric acid reacts with 11.5 grams of barium peroxide. How many grams of hydrogen peroxide are produced? H2SO4 + BaO2 = H2O2 + BaSO4

2.31 grams H2O2

What is the theoretical yield of vanadium, in moles, that can be produced by the reaction of 2.0 moles of V2O5 with 6.0 moles of calcium based on the following chemical reaction? V2O5(s) + 5Ca (l) = 2V(l) + 5Ca0(s)

2.4 mol

Express the number 26.7 in scientific notation.

2.67 x 10^1

5.0 x 10^80 molecules of CH3OH = _____ grams

2.7 x 10^58

Liquid hexane, C6H14, burns in oxygen gas to yield carbon dioxide and water. What is the minimum mass of oxygen required for the complete reaction of 10.0 mL of hexane? (density of hexane = 0.660 g/mL)

23.3 g

How many grams of MgSO4*7H20 must be used to have 120 grams of pure magnesium sulfate?

250 grams

You heated 45.0 grams of Al203*3H2O to drive off the water. How many grams of Al2O3 remained?

29.4 grams

How many grams of KClO3 must be decomposed to yield 1.20 grams of O2? KClO2 = KCl + O2

3.07 grams KClO3

Calculate the density of Bromine (in g/mL) if 586 g if the substance occupies 188 mL.

3.12 g/mL

Find the number of grams of Al2(SO4)3 which are found in 500 grams of Al2(SO4)3*18H20.

300 grams

How many grams are present in 4.32 x 10^24 molecules of carbon dioxide?

316 grams

The number 1.050 x 10^9 has how many significant figures?

4

125 grams of H2O = _____ molecules

4.18 x 10^24

How many moles of NH3 are there in 77.5 g of NH3?

4.55 mol

How many grams are in 0.02 moles of beryllium iodide?

5 grams

What is the percent of Ba? Ba(C2H3O2)2

53.78% Ba

How many grams of copper (II) oxide is formed by oxidizing 5.67 grams of copper metal? Cu + O2 = CuO

7.10 grams CuO

How many molecules are in 98.3 grams of aluminum hydroxide?

7.56 x 10^23 molecules

The mass of 1.63 x 10^21 silicon atoms is:

7.60 x 10^-2 g

What is the average mass, in grams, of one atom of iron?

9.28 x 10^-23 g

What is the percent of Al? Al(ClO3)3

9.73% Al

What is the percent of I? PI3

92.47% I

Which of the following elements is chemically similar to oxygen? A. sulfur B. calcium C. iron D. nickel E. sodium

A. sulfur

Write and balance this chemical equation: Silver nitrate and lead combine in a single displacement reaction to form lead (II) nitrate and silver.

AgNO3 + Pb = Pb(NO3)2 + Ag 2-1-1-2

Which of the following is a PHYSICAL property of sodium? A. Its surface turns black when first exposed to air. B. Its a solid at 25 degrees C and changes to a liquid when heated to 98 degrees C. C. When placed in water it sizzles and a gas is formed. D. When placed in contact with chlorine it forms a compound that melts at 801 degrees C. E. Sodium is never found as the pure metal in nature.

B. Its a solid at 25 degrees C and changes to a liquid when heated to 98 degrees C.

Which one of the following elements is most likely to form a 2- ion? A. scandium B. selenium C. silicon D. strontium E. iodine

B. selenium

Which of the following does NOT represent a CHEMICAL change? A. a freshly cut apple turns brown B. milk turns sour on standing at room temperature C. when cooled to 0 degrees C, liquid water becomes ice D. frying an egg E. fermentation of sugar to alcohol

C. when cooled to 0 degrees C, liquid water becomes ice

Acetate

C2H302 -1 charge

Find the empirical and molecular formula: C - 53.3% H - 11.1% O - 35.5% M.W. = 90.0 grams

C2H5O C4H10O2

An organic thiol compound is 38.66% C, 9.73% H, and 51.61% S by mass. What is the empirical formula of this compound?

C2H6S

Oxalate

C2O4 -2 charge

Find the empirical and molecular formula: C - 34.95% H - 6.84% O - 46.56% N - 13.59% M.W. = 100 grams

C3H7O3N C3H7O3N

Write and balance this chemical equation: Propane (C3H8) combusts with oxygen.

C3H8 + O2 = H2O + CO2 1-5-4-3

Find the empirical and molecular formula: C - 85.7% H - 14.3% M.W. = 42.0 grams

CH2 C3H6

Cyanide

CN -1 charge

Dichromate

Cr2O7 -2 charge

Chromate

CrO4 -2 charge

What is the correct formula for Copper (II) Phosphate?

Cu3(PO4)2

Which of the following pairs of elements would be most likely to form an ionic compound? A. P and Br B. Cu and K C. C and O D. O and Zn E. Al and Rb

D. O and Zn

The chemical formula for Iron (II) Nitrate is:

Fe(NO3)2

Dihydrogen Phosphate

H2PO4 -1 charge

Bicarbonate

HCO3 -1 charge

Bisulfate

HS04 -1 charge

Write and balance this chemical equation: Potassium nitrate reacts with zinc phosphate.

KNO3 + Zn3(PO4)2 = K3PO4 + Zn(NO3)2 6-1-2-3

Permanganate

MnO4 -1 charge

Ammonia reacts with diatomic oxygen to form nitric oxide and water vapor: 4NH3 + 502 = 4NO + 6H20 When 20.0 g NH3 and 50.0 g O2 are allowed to react, which is the limiting reagent?

NH3

Write and balance this chemical equation: Sodium reacts with nitric acid.

Na + HNO3 = NaNO3 + H2 2-2-2-1

Peroxide

O2 -2 charge

Thiosulfate

S2O3 -2 charge

Thiocyanate

SCN -1 charge

Silicate

SiO3 -2 charge

The element oxygen consists of three naturally occurring isotopes: 16O, 17O, 18O. The atomic mass of oxygen is 16.0 amu. What can be implied about the relative abundances of these isotopes?

The abundances of 17O and 18O are very small.

The correct name for NH4NO3 is:

ammonium nitrate

Chemical or physical change? A flashlight beam slowly gets dimmer and finally goes out.

chemical

Chemical or physical change? The growth of plants depends on the sun's energy in a process called photosynthesis.

chemical

Chemical or physical property? Uranium is a radioactive element.

chemical

Chemical or physical change? A spoonful of table salt dissolves in a bowl of soup.

physical

Chemical or physical change? Frozen orange juice is reconstituted by adding water to it.

physical

Chemical or physical change? The helium gas inside a balloon tends to leak out after a few hours.

physical

Determine the theoretical yield, identify the limiting reactant, and identify the excess reactant: How many grams of NaCl will form if 5.65 grams of KCl reacts with 7.82 grams of NaOH in the following reaction? KCl + NaOH = NaCl + KOH

Theoretical yield = 4.43 g NaCl Limiting reactant = KCl Excess reactant = NaOH

Determine the theoretical yield, identify the limiting reactant, and identify the excess reactant: If 6.55 grams of Pb(NO3)2 react with 10.0 grams of KI, how many grams of PbI2 will form? Pb(NO3)2 + KI = PbI2 + KNO3

Theoretical yield = 9.12 g PbI2 Limiting reactant = Pb(NO3)2 Excess reactant = KI