Exam #2 - Chemistry

0.0523 M

34.62 mL of 0.1510M NaOH was needed to neutralize 50.0mL of an H2SO4 solution. What is the concentration of the original sulfuric acid solution?

NH3

Ammonia reacts with diatomic oxygen to form nitric oxide and water vapor: 4NH3 + 5O2 --> 4NO + 6H2O When 20.0 g NH3 and 50.0g O2 are allowed to react, which is the limited reagent?

There are about one-fourth as many helium atoms as hydrogen atoms

An atom of helium has a mass about four times greater than that of an atom of hydrogen. Which choice makes the correct comparison of the relative numbers of helium and hydrogen atoms in equal masses of the two elements?

ethanol < Mg(NO3)2 < NaCl

Arrange the following aqueous solutions in order of increasing boiling points 0.050m Mg(NO3)2 ; 0.100m ethanol; 0.090m NaCl

9

Balance the following equation using the smallest set of whole numbers, then add together the coefficients. Don't forget to count coefficients of one. The sum of the coefficients is _ Al + H2SO4 --> _ Al2(SO4)3 + H2

9

Balance the following equation using the smallest set of whole numbers, then add together the coefficients. Don't forget to count coefficients of one. The sum of the coefficients is _ Cr + _ H2SO4 --> _ Cr2(SO4)3 + H2

no precipitate will form

Based on the solubility rules, which of the following will occur when solutions of ZnSO4(aq) and MgCl2(aq) are mixed?

BaSO4

Based on the solubility rules, which one of the following compounds should be insoluble in water?

AgNO3

Based on the solubility rules, which one of the following should be soluble in water?

14.8 grams

Calculate the mass of FeS formed when 9.42g of iron reacts with 8.50g of sulfur according to the following reaction. Fe(S) + S(s) --> FeS(s)

156 amu

Calculate the molecular mass of menthol, C10H20O.

HCl

Chlorine gas can be made from the reaction of manganese dioxide with hydrochloric acid. MnO2(s) + 4HCl(aq) --> MnCl2(aq) + 2H2O(l) + Cl2(g) According to the above reaction, which is the limiting reagent when 28g of MnO2 are reacted with 42g of HCl

The boiling point of the solution is always greater than the boiling point of the pure solvent

Consider a solution made from a nonvolatile solute and a volatile solvent. Which statement is true?

1.80 x 10^23 atoms

How many atoms are in 4.39g of CO2?

769 grams

How many grams of water are needed to dissolve 27.8 g of ammonium nitrate NH4NO3 in order to prepare a 0.452 m solution?

1.7 x 10^-5 mol

How many moles of HCL are represented by 1.0 x 10^19 HCl molecules?

2.14 x 10^22 atoms

How many silicon atoms are there in 1.00g of silicon?

Br is oxidized and Cl is reduced

Identify the elements that are oxidized and reduced in the following equation KClO3(aq) + 6HBr(aq) --> KCl(aq) + 3Br2(l) + 3H2O(l)

H+, HSO4-

Identify the major ionic species present in an aqueous solution of H2SO4.

combination

Model: A + B --> C Identifying factor: one product

single replacement

Model: A + BC --> B + AC Identifying factor: one element, one compound

combustion

Model: A + O2 --> AxOy Identifying factor: one reactant must be oxygen

decomposition

Model: A --> B + C Identifying factor: one reactant into element or compounds

double replacement

Model: AB + CD --> CB + AD Identifying factor: two aqueous ionic compounds (reactant)

hydrocarbon combustion

Model: CxHy CxHyOz Identifying factor: if other reactant is a hydrocarbon then products are CO2 and H2O - reacts with O to make carbon dioxide, water, and heat

none of the above

One mole of iron

Na2SO4

Select the compound in which sulfur has its highest possible oxidation number

The abundances of 17O and 18O are very small

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

2.77 x 10^-3 molecules

The molecular formula of aspirin is C9H8O4/ How many spirit molecules are present in one 500-milligram tablet?

none of the above

The oxidation number of Cl in ClO4- is?

+6

The oxidation number of S in K2SO4 is?

C18H36O2

The percent composition by mass of a compound is 76.0% C, 12.8% H, and 11.2% O. The molar mass of this compound is 284.5 g/mol. What is the molecular formula of the compound?

C2H3Cl

The percent composition by mass of an unknown chlorinated hydrocarbon was found to be 37.83% C, 6.35% H, and 55.83% Cl by. mass. What is the empirical formula of this compound?

12

What is the coefficient of H2O when the following equation is properly balanced with smallest set of whole numbers? _ Al4C3 + _ H2O --> _Al(OH)3 + _ CH4

-17.6 C

What is the freezing point of a solution prepared from 50.0g ethylene glycol (C2H6O2) and 85.0g H2O? Kf of water is 1.86 C/m

none of these

What is the mass of 0.20 mole of C2H6O (ethanol)?

92.6 g/mol

What is the molar mass of toluene if 0.86g of toluene depresses the freezing point of 100 g of benzene of 0.47C? Kf of benzene is 5.12 C/m

2.4 mol

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

3.11 grams

What mass of Na2SO4 is needed to prepare 350 mL of a solution having a sodium ion concentration of 0.125 M?

21

When a chemical equation is balanced, it will have a set of whole number coefficients that cannot be reduced to smaller whole numbers. What is the coefficient for O2 when the following combustion reaction of a hydrocarbon is balanced? _ C7H14 + _ O2 --> _ CO2 _ H2O

+2, +1, -2

Which choice gives the correct oxidation numbers for all three elements in Ca(ClO)2 in the order that the elements are shown in the formula?

0.15m Na2SO4

Which of the follow aqueous solutions has the lowest freezing points? A) 0.18m KCl B) 0.15m Na2SO4 C) 0.12m Ca(NO3)2 D) pure water E) 0.20m C2H6O2 (ethylene glycol)

C2H5O (ethanol)

Which of the following compounds is a non electrolyte?

KOH

Which of the following compounds is a strong electrolyte?

2NaCl + Pb(NO3)2 --> PbCl2 + 3NaNO3

Which of the following equations does not represent an oxidation-reduction reaction? A) 3Al + 6HCL --> 3H2 + AlCL3 B) 2H2o --> 2H2 + O2 C) 2NaCl + Pb(NO3)2 --> PbCl2 + 3NaNO3 D) 2NaI + Br2 --> 2NaBR + I2 E) Cu(NO3)2 + Zn --> Zn(NO3)2 + Cu

Fe2O3(s) + 2Al(s) --> 2Fe(s) + Al2O3(s)

Which of the following represents a metal displacement reaction? A) 2NaN3(s) --> 2Na(s) + 3N2(g) B) Fe2O3(s) + 2Al(s) --> 2Fe(s) + Al2O3(s) C) 3NO2(g) + H2O(l) --> 2HNO3(aq) + NO(g) D) 2P(s) + 3Cl2(g) --> 2PCl3(g) E) 2ZnS(s) + 3O2(g) --> 2ZnO(s) + 2SO2(g)