Chem exam weeks 5-8

Like all noble gases, xenon (Xe) is quite unreactive. Determine the number of moles of Xe that are present in a 12.0 g sample of this gas.

0.0914 mol

Cesium, Cs, is a highly reactive alkali metal. If you have 50.0 g of Cs, how many moles of Cs are in the sample?

0.376 mol

Calcium sulfate, CaSO 4, is an insoluble ionic compound. Determine the moles of oxygen atoms present in a 25.7 gram sample of calcium sulfate.

0.755 mol

Determine the total number of atoms present in 0.0728 grams of phosphorus trichloride, PCl 3.

1.28 × 10 21 atoms

Balance the equation below, using the smallest integer coefficients. Next, determine the sum of the coefficients. __ CH 4 (g) + ___ Cl 2 (g) ___ CCl 4 (g) + ___ HCl (g) The sum of the coefficients is :

10

Calculate the molar mass of iron (II) cyanide, Fe(CN)2. Report your answer to 4 significant figures. Report your answer using decimal notation, NOT scientific notation.

107.9

Organic molecules are responsible for many of the flavors in food. Calculate the molar mass of the following compound, which imparts a minty flavor to food: C 10H 20O

156 g/mol

Oxidizing agents, such as potassium permanganate, are used extensively in organic synthesis. Determine the molar mass of this important compound, which has the chemical formula KMnO 4.

158 g/mol

Determine the mass percent composition of phosphorus in calcium phosphate, an ingredient in some calcium supplements. Its chemical formula is Ca 3(PO 4) 2.

19.97 %

Copper forms a green patina coating when exposed to the environment. If you have 3.14 grams of Cu, how many Cu atoms do you have?

2.98 × 10 22

Balance the equation below, using the smallest integer coefficients. What is the coefficient of water?___ PCl 3 (l) + ___ H 2O (l) → ___ H 3PO 3 (aq) + ___ HCl (aq)

3

The reaction of ethene with oxygen has the following unbalancedequation C2H4(g) + O2(g) → CO2(g) + H2O(l) The coefficient for oxygen in the balanced equation is ...

3

Aluminum is a strong, lightweight metal. How many moles of aluminum are present in a 96.7 gram sample of this metal?

3.58 mol

The reaction of acetone with oxygen has the following unbalancedequation C3H6O(l) + O2(g) → CO2(g) + H2O(l) The coefficient for oxygen in the balanced equation is...

4

Potassium bromide (KBr) is a soluble ionic compound. How many cations and anions are present in a 8.38 g sample of potassium bromide?

4.24 × 10 22 K +; 4.24 × 10 22 Br

What is the mass percent of sodium in Na2CO3?

43.38%

Balance the equation below, using the smallest integer coefficients. Next, determine the sum of the coefficients. ___ Cr (s) + ___ H 2SO 4 (aq) ___ Cr 2(SO 4) 3 (aq) + ___ H 2 (g)

9

Balance the equation below, using the smallest integer coefficients. Next, determine the sum of the coefficients. The sum of the coefficients is: __ SF 4 (g) + __ H 2O (l) __ H 2SO 3 (aq) + __ HF (aq) The sum of the coefficients is:

9

Balance the equation below, using the smallest integer coefficients. Next, determine the sum of the coefficients.___ Al (s) + ___ H 2SO 4 (aq) ___ Al 2(SO 4) 3 (aq) + ___ H 2 (g) The sum of the coefficients is:

9

Calculate the mass of 1.00 iron atom in grams.

9.27 x 10-23 grams

explain the difference between a diatomic element and a diatomic compound.

A diatomic element contains two of the same atom; a diatomic compound contains two different atoms.

Using your own words, define "polyatomic ion"

A polyatomic ion is composed of two or more covalently bonded atoms that together share positive or negative charge(s)

molecular compound

B2H6

Using your understanding of relative boiling points, which substance listed below would you predict has the lowest boiling point?

CH4

Write the formula of the compound formed between the calcium ion and the nitrate ion.

Ca(NO3)2

Which one of the ionic compounds listed below cannot possibly exist?

Ca2S

Which formula below represents calcium phosphate?

Ca3(PO4)2

Which formula below represents calcium hydrogen phosphate?

CaHPO4

Write the formula of the compound formed when calcium and selenium react with one another.

CaSe

Which one of the ionic compounds listed below cannot possibly exist?

Cd2P3

What is the classification of the reaction: 6 Ca(s) + P4(s) → 2 Ca3P2(s)

Combination

which formula below represents copper (II) cyanide?

Cu(CN)2

What is the classification of the reaction: NH4NO2(aq) → N2(g) + 2 H2O(l)

Decomposition

What is the classification of the reaction: Mg(OH)2(aq) + 2 HCl(aq) → MgCl2(aq) + 2 H2O(l)

Double displacement

Avogadro's number tells us how many grams of a substance are present on one mole of that substance.

False

Which chemical formula listed below belongs to iron (II) nitrate?

Fe(NO3)2

Which of the following is the formula for hydrobromic acid?

HBr

Your friend tells you that the chemical formula of the compound formed between Ca2+ and S2- is as "Ca2S2". Why is it incorrect to write the formula that way?

Ionic formulas must be written using the lowest possible ratio of cations and anions.

Which statement below most accurately describes carbon monoxide, CO?

It is a diatomic molecule containing atoms of different elements.

Which formula below represents the compound formed between potassium and nitrogen?

K3N

What is the formula for the ionic compound formed by magnesium and iodine?

MgI2

Which formula below represents magnesium sulfate?

MgSO4

Which formula below represents sodium sulfide?

Na2S

ionic compound

NaBr

Using your understanding of relative boiling points, which substance listed below would you predict has the highest boiling point?

PbCO3

Which formula below represents lead (II) carbonate?

PbCO3

What is the classification of the reaction: Bi2O3(s) + 3 Zn(s) → 3 ZnO(s) + 2 Bi(s)

Single displacement

What is the classification of the reaction: Ca(s) + 2 H2O(l) → Ca(OH)2(aq) + H2(g)

Single displacement

What is the formula of the binary compound formed between strontium and chlorine?

SrCl2

A student writes the chemical formula of the compound formed between NH4+ and SO42- as "NH42SO4". Why is it incorrect to write the formula that way?

We need to place parentheses around polyatomic ions whenever there is more than one of that polyatomic ion in the chemical formula. Without the parentheses, it looks like the subscript applies only to the last element in the polyatomic ion. The formula "NH42SO4" suggests that there is 1 nitrogen, 42 hydrogens (!), 1 sulfur, and 4 oxygens in the chemical formula.

onsider the chemical formulas shown below. Is it likely that the substance will be a solid at room temperature? If it must be a solid at room temperature, type "Yes" in the field next to the chemical formula. If it may be a physical state OTHER than solid a room temperature, type "No" in the field next to the chemical formula. HBr: [a] Na3PO4: [b] C5H12: [c] Fe3(PO4)2: [d] Cu2O3: [e]

a: No b: Yes c: No d: Yes e: Yes

For each of the following substances, determine whether the substance is ionic or molecular. Type "ionic" if it is an ionic substance or "molecular" if it is a molecular substance. N2O5: [a] NH4Cl [b] CO2: [c] NaF: [d] H2: [e]

a: molecular b: ionic c: molecular d: ionic e: molecular

Give the systematic name of the following compound: NH 4NO 3

ammonium nitrate.

Give the systematic name of the following compound: Ba(OH) 2

barium hydroxide.

Give the systematic name of the following compound: CrSO3

chromium (II) sulfite

The reaction 3O2(g) + 2Al(s) → Al2O6(s) is an example of a(n)

combination

The reaction 2AgNO3(aq) + BaCl2(aq) → 2AgCl(aq) + Ba(NO3)2(aq) is an example of a(n)

double replacement

Is the compound PbSO4 soluble or insoluble in water?

insoluble

Is the compound SrSO4 soluble or insoluble in water?

insoluble

Is the compound Zr3(PO4)2 soluble or insoluble in water?

insoluble

Give the systematic name of the following compound: Mn 2O 7

manganese (VII) oxide.

Which combination listed below is most likely to form ionic compounds?

metals and halogens

How many insoluble products will be formed when the following two solutions are mixed together? K2S(aq) + CaCl2(aq) -->

one soluble product

Give the systematic name of the following compound: KClO.

potassium hypochlorite

Is the compound CsOH soluble or insoluble in water?

soluble

Is the compound TiSO4 soluble or insoluble in water?

soluble

Members of which group listed below can form cations with multiple different charges (i.e. which group forms variable charge cations)?

transition metals

5 g of hydrogen molecules contains the same number of hydrogen atoms as 5 g of hydrogen atoms.

true