Chem exam 3

what is the molarity of potassium ions in a 0.122 m k2cro4 solution

0.122 m K2CrO4 * 2 K+ = 0.244 M K+

How many moles of HCl are there in 75.0 mL of 0.150 M HCl?

0.150 M HCl * 0.0750 L = 0.01125 moles HCl

What is the concentration of sodium ions in 0.300 M Na₂CO₃?

0.300 * 2= 0.600 M -- you take the concentration and multiply it by the number of sodium atoms in the formula

What volume in L of 0.724 M NaI solution contains 0.405 mol of NaI ?

0.405 mol NaI * (1L / 0.724 mol NaI) = 0.559 L

double bond

1 sigma + 1 pi bond

triple bond

1 sigma + 2 pi bond

single bond

1 sigma bond

What is the mass percentage of Cl in hydrochlorothiazide, C₇H₈ClN₃O₄S₂?

11.91%

Balance the following chemical equation (if necessary): Balance the following chemical equation (if necessary): C₃H₆(g)+O₂(g)→CO₂(g) +H₂O(g)

2C₃H₆(g)+9O₂(g)→6CO₂(g)+6H₂O(g)

What is the mass percentage of C in morphine, C₁₇H₁₉NO₃?

71.54%

What is the mass percentage of O in CO₂?

72.71%

Which of the following molecules has a bond order of 1.5 according to molecular orbital theory? A) B₂⁻ B) N₂⁻ C) CN⁻ D) NO⁻

A) B₂⁻ -- BO=12(number of bonding electrons − number of antibonding electrons) BO = 12( number of bonding electrons − number of antibonding electrons) BO = 12(5−2)=1.5

What type of reaction is represented by the following equation: KOH(aq) + NH₄Cl(aq) → NH₃(aq) + KCl(aq) + H₂O(l) A) acid-base B) decomposition C) precipitation D) redox (oxidation-reduction)

A) acid-base - This is an acid-base reaction, which involves the transfer of a proton from one species (the acid, in this case NH₄⁺) to another (the base, in this case OH⁻).

A 5.31 g sample of compound that contains only hydrogen and sulfur was combusted, and yielded 10.0 g of SO₂ and 2.81 g of H₂O. The molar mass of the compound is 68 g/mol. What is this compound's molecular formula? A) H₄S₂ B) H₂S C) HS D) H₂S₂

A. H4S2

Water is a polar molecule because A. water is a bent molecule and oxygen is more electronegative than hydrogen B. oxygen is a nonmetal and hydrogen is a metal C. the hydrogen atoms only have one electron each while the oxygen atom has 8 electrons D. water is an ionic compound

A. water is a bent molecule and oxygen is more electronegative than hydrogen

Which atomic orbitals from carbon hybridize to form the bonds in CH₄? A) 1s, 2pₓ, 2p_y, 2p_z B) 2s, 2pₓ, 2p_y, 2p_z C) 3s, 3pₓ, 2p_y, 2p_z D) 2s, 2pₓ, 2p_y

B) 2s, 2pₓ, 2p_y, 2p_z

According to molecular orbital theory, place the following molecules in order of increasing bond energy CN, CN⁺, and CN⁻.

B) CN⁺ < CN < CN⁻

What is the molecular formula of a compound that contains only carbon and hydrogen, is 85.6% carbon, and has a molar mass of 70 g/mol? A) CH₂ B) C₅H₁₀ C) C₅H₅ D) C₄H₂₁

B) C₅H₁₀

Which of the following molecules is considered most stable according to molecular orbital theory? A) H₂⁻ B) H₂ C) He₂ D) He₂⁺

B) H₂ -- Draw the MO diagram for each molecule and think about the number of bonding and antibonding electrons. Higher bond order also indicates higher stability. H₂ is the most stable.

The ions formed when MgI₂ dissociates in water are A. Mg²⁺ and I2⁻ B. Mg²⁺ and I⁻ C. Mg⁺ and I⁻ D. Mg⁺ and I2⁻ E. No ions, MgI2 does not dissociate

B. Mg²⁺ and I⁻ on the periodic table, Mg is 2+ and I is -1 charges

A compound that contains only carbon, hydrogen, and oxygen is 68.5% C and 8.63% H by mass. What is the empirical formula of this substance? A) C₃H₅O B) C₆H₄ C) C₄H₆O D) C₄H₈O₂

C) C₄H₆O

Which of the following molecules is considered least stable according to molecular orbital theory? A) H₂⁻ B) H₂ C) He₂ D) He₂⁺

C) He₂ --High bond orders indicate high stability. He₂ is the least stable.

What type of reaction is represented by the following equation: CoCl₂(aq) + 2NaOH(aq) → Co(OH)₂(s) + 2NaCl(aq) A) acid-base B) decomposition C) precipitation D) redox (oxidation-reduction)

C) precipitation - This is a precipitation reaction, which involves the formation of an insoluble solid and an aqueous solution.

What numbers belong in the blank spaces to fully balance the following reaction? __Fe (s) + __Cl₂ (g) → __FeCl₃ (s) A. 1, 1, 1 B. 1, 2, 1 C. 2, 3, 2 D. 2, 2, 2 E. 3, 3, 2

C. 2, 3, 2

Give the balanced equation for solid iron(III) sulfide reacting with gaseous hydrogen chloride to form solid iron(III) chloride and hydrogen sulfide gas. A. Fe2S3 (s) + HCl (g) --> FeCl3 (s) + H2S (g) B. Fe2(SO4)3 (s) + 6 HCl (g) --> 2 FeCl3 (s) + 3 H2S (g) C. Fe₂S₃ (s) + 6 HCl (g) → 2 FeCl₃ (s) + 3 H₂S (g) D. Fe3S (s) + HCl (g) --> Fe3Cl (s) +H2S (g)

C. Fe₂S₃ (s) + 6 HCl (g) → 2 FeCl₃ (s) + 3 H₂S (g)

Balance the following chemical equation (if necessary): Ca(C₂H₃O₂)₂ (aq) + Na₂CO₃ (aq)→ CaCO₃ (s) + NaC₂H₃O₂ (aq)

Ca(C₂H₃O₂)₂ (aq) + Na₂CO₃ (aq)→ CaCO₃ (s) + 2 NaC₂H₃O₂ (aq)

Balance the following chemical equation (if necessary): C₅H₁₀O (l) + O₂ (g) → H₂O (g) + CO₂ (g)

C₅H₁₀O (l) + 7O₂ (g) → 5H₂O (g) + 5CO₂ (g)

Balance the following chemical equation (if necessary): C₆H₆O (l) + O₂ (g) → H₂O (g) + CO₂ (g)

C₆H₆O (l) + 7 O₂ (g) → 3 H₂O (g) + 6 CO₂ (g)

The molecular orbital energy diagram for N₂ is shown below. Based on this diagram, what is the bond order of N₂?

D) 3 -- BO=12 (number of bonding electrons − number of antibonding electrons) BO =12 (number of bonding electrons − number of antibonding electrons) BO = 12(10−4)=3

What type of reaction is represented by the following equation: C₄H₈(g) + 6O₂(g) → 4CO₂(g) + 4H₂O(g) A) acid-base B) decomposition C) precipitation D) redox (oxidation-reduction)

D) redox (oxidation-reduction) - This is a redox equation, which involves the oxidation (loss of electrons) and reduction (gain of electrons) between species in the reaction.

Which molecule contains sp hybridized orbitals? A) C₂H₆ B) CH₄ C) C₂H₄ D) C₃H₄

D. C₃H₄

Draw the Lewis structure of BeH₂ and then determine if the molecule is polar or nonpolar.

H---Be---H non polar

To what volume would you need to dilute 20.0 mL of a 1.40 M solution of LiCN to make a 0.0900 M solution of LiCN?

M1V1=M2V2 V2= M1V1/M2 (20.0 mL * 1.40 M)/ 0.0900 M LiCN = 311 mL

Balance the following chemical equation (if necessary): NH4NO2 (s) --> N2(g) + H2O(l)

NH4NO2 (s) --> N2(g) + 2H2O(l)

What is the mass percent of water in nickel(II) sulfate hexahydrate?

NiSO4(H2O)6 41.12%

diamagnetic

all paired electrons

What is the concentration of a solution made with 0.150 moles of KOH in 400.0 mL of solution?what is the molarity of potassium ions in a 0.122 m k2cro4 solution

molarity= moles of solute/liters of solution 0.150 moles of KOH/0.400 L of solution= 0.375 M

paramagnetic

unpaired electrons