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General Chemistry I Exam Review Answers, Exams of Chemistry

Answers to exam questions from a General Chemistry I course, covering topics such as predicting products of reactions, identifying gases formed during metathesis reactions, redox reactions, and solving problems related to moles, liters, and thermochemistry. Students are expected to have a thorough understanding of all material presented in lectures and on the topics list.

What you will learn

  • What are the products of the given reactions and in which phase do they form?
  • Which gases typically form during a metathesis reaction?
  • What are the oxidation numbers and what is oxidized, reduced, oxidizing agent, and reducing agent for each reaction?

Typology: Exams

2021/2022

Uploaded on 02/24/2022

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jamal33 🇺🇸

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F ‘08
REVIEW ANSWERS …EXAM 2
GENERAL CHEMISTRY I
These questions represent only a random sample of possible types of exam
questions. Students should be knowledgeable about all material presented during
lecture and on the topics list.
1) Predict the products resulting from these aqueous reactions
(include phase labels):
a) KNO3 + NaI KI (aq) and NaNO3 (aq)
b) Na2SO3 + HCL NaCL (aq) and H2O (l) and SO2 (g)
c) BaCL2 + Na2SO4 NaCL (aq) and BaSO4 (s)
d) HNO3 + KOH H2O (l) and KNO3 (aq)
2) List the three gases that can typically form during a “metathesis” reaction.
H2S, CO2 and SO2
3) Assign oxidation numbers and determine what is oxidized, reduced,
oxidizing agent, and reducing agent for each of the following reactions:
a) BaBr2 + 2 NaNO3 Ba(NO3)2 + 2 NaBr
Atom Reactant side Product side
Ba +2 +2
Br -1 -1
Na +1 +1
N +5 +5
O -2 -2
NO REDOX (no change in oxidation numbers)
b) H2SO4 + Na Na2SO4 + H2
Atom Reactant side Product side
H +1 0
S +6 +6
O -2 -2
Na 0 +1
H atom changed from +1 0 (reduced); H2SO4 oxidizing agent
Na atom changed from 0 +1 (oxidized); Na reducing agent
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REVIEW ANSWERS …EXAM 2

GENERAL CHEMISTRY I

These questions represent only a random sample of possible types of exam questions. Students should be knowledgeable about all material presented during lecture and on the topics list.

  1. Predict the products resulting from these aqueous reactions (include phase labels): a) KNO 3 + NaI  KI (aq) and NaNO 3 (aq) b) Na 2 SO 3 + HCL  NaCL (aq) and H 2 O (l) and SO 2 (g) c) BaCL 2 + Na 2 SO 4  NaCL (aq) and BaSO 4 (s) d) HNO 3 + KOH  H 2 O (l) and KNO 3 (aq)
  2. List the three gases that can typically form during a “metathesis” reaction. H 2 S, CO 2 and SO 2
  3. Assign oxidation numbers and determine what is oxidized, reduced, oxidizing agent, and reducing agent for each of the following reactions: a) BaBr 2 + 2 NaNO 3  Ba(NO 3 ) 2 + 2 NaBr Atom Reactant side Product side Ba +2 + Br - 1 - 1 Na +1 + N +5 + O - 2 - 2 NO REDOX (no change in oxidation numbers) b) H 2 SO 4 + Na  Na 2 SO 4 + H 2 Atom Reactant side Product side H +1 0 S +6 + O - 2 - 2 Na 0 + H atom changed from +1  0 (reduced); H 2 SO 4 oxidizing agent Na atom changed from 0  +1 (oxidized); Na reducing agent
  1. Look at the Activity Series to answer this question. An industrial chemist wants to purchase a large pot to use to brew very acidic beer. This pot will routinely hold H

ions. Which pot would be less likely to dissolve with continued use, a nickel pot or a copper pot? Explain. Use the copper pot. The Activity Series shows that H

ions do not appear below the Cu metal on the table, so copper will not be oxidized/dissolved by acid H

ions.

  1. How many moles of CaS are in 255 mL of a 1.25 M CaS solution? M = mol solute / L solution; rearrange to mol solute = ML mol solute = (1.25 mol/L) (0.255 L) =0.319 mol / L or M (Did you remember to convert mL to L?)
  2. How many liters of 3.00 M HI would be needed to neutralize 50.0 mL of 8.00 M Mg(OH) 2? The balanced equation is Mg(OH) 2 + 2 HI  2 H 2 O + MgI 2 8.00 mol Mg(OH) 2 2 mol HI 1 L HI 0.0500 L OH-^ ________________ ------------------ ___________ = 0.267 L 1 L Mg(OH) 2 1 mol Mg(OH) 2 3.00 mol HI (3 sf data)
  3. Consider the following thermochemical equation: 2 Mg + O 2  2 MgO ΔH = - 1204 kJ What would be the enthalpy change if 24.31 g Mg reacts? 24.31 g Mg ( 1 mol Mg / 24.31 g ) ( - 1204 kJ / 2 mol Mg) = - 602.0 kJ (4 sf) Did you relate the ΔH to the 2 moles of Mg as expressed in the equation?
  1. Ultraviolet radiation has a higher frequency than microwave radiation. Which of these two types of radiation would have the longer wavelength? Microwaves. Wavelength is inversely related to frequency, so the lower frequency radiation would have the longer wavelength.
  2. Calculate the frequency of 746 nm light, THEN calculate the energy of 1 photon of that light. Know your Greek! You are given wavelength (λ ), but need frequency (ν) to use Planck's relationship. 3.00 X 10 8 m s
  • 1 1 x 10 9 nm ν = c / λ = ------------------------- ------------------ = 4.02 X 10 14 s
  • 1 746 nm 1 m THEN… E = n h ν = (1) (6.626 X 10
  • 34 J • s) (4.02 X 10 14 s
  • 1 ) = 2.66 X 10
  • 19 J
  1. The symbol ψ (psi) represents what concept? ψ (psi) represents the wavefunction; this describes the path that an electron can travel around a nucleus.
  2. Is the following set of four quantum numbers possible? EXPLAIN. n l ml ms 3 1 0 - 1/ This set CAN exist. When n = 3, l can be 0, 1, or 2. THEN, when l =1, ml can be - 1, 0 or - 1. The value - 1/2 is allowed for ms.
  3. Which one of the following is the ground state electron configuration of the element magnesium? a) 1s 2 2s 2 2p 6 3s 1 b) 1s 2 2s 2 2p 6 3s 1 3p 1 c) 1s 2 2s 2 2p 6 3s 2 (c) 1s 2 2s 2 2p 6 3s 2 This configuration shows the lowest to highest orbitals filled in order for a twelve electron system.
  1. For the ground state of the element antimony (Sb)… a) write the electron configuration b) draw the orbital diagram c) count the number of valence electrons d) indicate the number of unpaired electrons e) indicate whether it is diamagnetic or paramagnetic (a) [Kr] 5s 2 4d 10 5p 3 ↑ ↑ ↑ (b) ___ ___ ___ 5p 5p 5p (c) 5 valence electrons (the highest "n" electrons) (d) 3 unpaired electrons (they do not pair unless forced to) (e) This is a paramagnetic substance since it has at least one unpaired electron. coffee cup calorimeter quantum "s" orbital Bumper sticker seen on a car: (can't be sure if this is true)