1
A Bronsted Lowrey acid is a substance which
What is a conjugate acid–base pair in the reaction HI + H₂O ⇌ H₃O⁺ + I⁻?
A. H₂O and HI
B. HI and H₃O⁺
C. H₂O and H₃O⁺
D. H₃O⁺ and I⁻
donates protons(H+) to other substances
ACID->BASE
BASE->BASE
Expressed to the correct number of significant figures, what is the correct sum of (2.10 g + 33.566 g + 12.221 g)? also explain the rule for addition and subtraction
What is 2.1 x 10-5 in standard notation?
47.89
0.000021
1.) Which equation represents a physical change?
A. CaCO₃ (s) → CaCO₃ (aq)
B. Mg (s) + 2AgNO₃ (aq) → Mg(NO₃)₂ (aq) + 2 Ag (s)
C. KOH (aq) + HCl (aq) → KCl (aq) + H₂O (l)
D. 2H₂ (g) + O₂ (g) → 2 H₂O (l)
Given the particle diagram representing four molecules of a substance, which particle diagram best represents the same substance after a physical change has taken place?...also draw reactant and products.
A. Molecules break apart into individual atoms
B. Molecules change into different shapes and sizes
C. Molecules stay the same but move closer together in a new arrangement
D. Molecules form completely new combinations with different atoms
A
C
Given the reaction at equilibrium:
N₂(g) + 3 H₂(g) ⇌ 2 NH₃(g)
The correct equilibrium expression for this reaction is:
Given the reaction at equilibrium:
H2(g) + Cl2(g) ⇌ 2 HCl(g) + heat
The equilibrium will shift to the right when:
A. concentration of HCl is increased
B. concentration of H2 is increased
C. pressure is increased
D. temperature is increased
[NH3]2 / [N2][H2]3
B
How many covalent bonds do they form?
H___C___Si___N___O___S___Cl___F___Br___
1, 4, 4, 3, 2, 2, 1, 1, 1
If the concentration of OH⁻ in an aqueous solution is 1.9 × 10⁻⁷ M, the concentration of H₃O⁺ is
A. 1.6 × 10⁻⁴ M
B. 2.6 × 10⁻¹¹ M
C. 5.3 × 10⁻⁸ M
D. 1.9 × 10⁻²¹ M
The pOH of a solution with [H₃O⁺] = 2.6 × 10⁻⁸ M, to the correct number of significant figures, is
A. 6.41
B. 2.65 × 10⁻⁸
C. 7.6
D. 7.58
E. 6.4
Kw = 1.0 × 10⁻¹⁴
[H₃O⁺] = Kw / [OH⁻]
[H₃O⁺] = (1.0 × 10⁻¹⁴) ÷ (1.9 × 10⁻⁷)
[H₃O⁺] = 5.26 × 10⁻⁸
= 5.3 × 10⁻⁸ M
Correct answer: C
pH = −log[H₃O⁺]
pH = −log(2.6 × 10⁻⁸)
pH = 7.59
pOH = 14 − pH
pOH = 14 − 7.59 = 6.41
Correct answer: A
How many mL of 24.2 M LiOH are needed to prepare 474 mL of a 2.16 M solution?
A. 11.0 mL
B. 53.1 mL
C. 42.3 mL
D. 26.6 mL
C
Given the reaction:
Cu + 4 HNO3 → Cu(NO3)2 + 2 H2O + 2 NO2
What is the total mass of H2O produced when 32.7 grams of Cu is completely consumed?
A. 9.3 g
B. 18.5 g
C. 65.4 g
D. 32.7 g
General equations:
moles = mass ÷ molar mass
moles product = moles reactant × (coeff product / coeff reactant)
mass = moles × molar mass
How to find the limiting reactant (if both were given):
moles Cu ÷ 1
moles HNO3 ÷ 4
the smaller value = limiting reactant
In this problem:
Only Cu amount is given → Cu is the limiting reactant.
Work:
moles Cu = 32.7 ÷ 63.55 = 0.5147 mol
moles H2O = 0.5147 × (2/1) = 1.029 mol
mass H2O = 1.029 × 18 = 18.5 g
Correct answer: B
Consider the reaction shown:
2 Mn + O₂ → 2 MgO + 72 kcal
We can say that this reaction is ______ and that the sign of ΔH is ______.
A. exothermic; positive
B. endothermic; negative
C. exothermic; neither positive nor negative
D. exothermic; negative
E. endothermic; positive
D
element with electron configuration 1s2 2s2 2p6 3s2 3p5 is?
element with electron configuartion 1s2 2 s2 2p6 3s2 is?
Cl
Mg
A balloon filled with helium gas at 18.6 °C occupies 3.31 L at 0.834 atm. The balloon is then immersed in a liquid, changing the pressure to 4.3 atm and the volume to 0.226 L.
What is the final temperature (in °C) of the balloon?
P₁V₁ / T₁ = P₂V₂ / T₂
T₁ = 18.6 + 273 = 291.6 K
T₂ = (P₂ V₂ T₁) / (P₁ V₁)
T₂ = (4.3)(0.226)(291.6) / (0.834)(3.31)
T₂ ≈ 103 K
T(°C) = 103 − 273
= −170 °C
Iodine-131 has a half-life of 8.0 days. What percentage of a sample will remain after 12 days?
Fraction = (1/2)^(t ÷ half-life)
t = 12
half-life = 8
(1/2)^(12 ÷ 8)
12 ÷ 8 = 1.5
(1/2)^1.5 = 0.354
0.354 × 100 = 35.4%
4 Al + 3 O2 → 2 Al2O3
4.56 mol of Al reacts with excess oxygen. If 217.5 g of Al2O3 is recovered, what is the percent yield?
A. 95.6%
B. 93.5%
C. 46.9%
D. 46.8%
General equations:
moles product = moles reactant × (coeff product / coeff reactant)
mass = moles × molar mass
percent yield = (actual / theoretical) × 100
Work:
moles Al2O3 = 4.56 × (2/4) = 2.28 mol
theoretical mass = 2.28 × 102 = 232.56 g
percent yield = (217.5 / 232.56) × 100 = 93.5%
Correct answer: B
What is the formula for the ionic compound formed between sodium and fluoride?
What is the formula for the ionic compound formed between potassium and oxygen?
What is the formula for the following compound? chromium (VI) nitrate
What is the systematic name of ICl3
NaF
K2O
Cr(NO3)6
iodine trichloride
What is the osmolarity of a 3.25 M solution of LiOH?
A. 13.0 Osmol
B. 6.50 Osmol
C. 3.25 Osmol
D. 13.6 Osmol
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What is the osmolarity of a 3.74 M solution of MgCl₂?
A. 22.4 Osmol
B. 11.2 Osmol
C. 3.74 Osmol
D. 5.89 Osmol
LiOH dissociates into 2 particles:
Li+ and OH-
osmolarity = molarity * number of particles
osmolarity = 3.25 * 2 = 6.50 Osmol
Correct answer: B
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MgCl2 dissociates into 3 ions:
Mg2+ and 2 Cl-
number of particles = 3
osmolarity = molarity * number of particles
osmolarity = 3.74 * 3 = 11.22 Osmol
round → 11.2 Osmol
Correct answer: B
What is the mass of 40.0 mL of a solution with a density of 1.80 g/mL?
A. 0.045 g
B. 1.60 g
C. 72.0 g
D. 41.8 g
density = mass / volume
mass = density × volume
mass = 1.80 g/mL × 40.0 mL
mass = 72.0 g
Correct answer: C
What is the missing reactant in the reaction shown?
³⁵₁₇Cl + ______ → ³²₁₆P + ⁴₂He
A. ¹₀n
B. ⁴₂He
C. ¹₁H
D. ⁰₋₁β
E. ²₁H
Use conservation of mass number and atomic number:
Mass numbers:
35 + X = 32 + 4
35 + X = 36
X = 1
Atomic numbers:
17 + Z = 16 + 2
17 + Z = 18
Z = 1
Particle with A = 1 and Z = 1 is: ¹₁H
Correct answer: C
How many grams of O₂ are contained in a 7.22 L sample at 0.85 atm and 26.7°C?
A. 0.230 g
B. 139 g
C. 7.98 g
D. 89.6 g
PV = nRT
T = 26.7 + 273 = 299.7 K
n = (0.85 × 7.22) ÷ (0.0821 × 299.7) = 0.249 mol
mass = moles × molar mass
mass = 0.249 × 32 = 7.98 g
Correct answer: C
What is the molarity of a solution prepared by dissolving 58.4 g of LiOH in enough water to make a 193 mL solution?
A. 3.30 M
B. 6.32 M
C. 7.25 M
D. 12.6 M
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What is the normality of a solution prepared by dissolving 63.6 g of Ca(OH)₂ in enough water to make a 485 mL solution?
A. 3.54 N
B. 1.77 N
C. 9.72 N
D. 7.63 N
molar mass LiOH = 23.95 g/mol
moles = mass ÷ molar mass
moles = 58.4 ÷ 23.95 = 2.438 mol
volume = 193 mL = 0.193 L
M = mol ÷ L
M = 2.438 ÷ 0.193 = 12.6 M
Correct answer: D
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molar mass Ca(OH)2 = 74.10 g/mol
moles = 63.6 / 74.10 = 0.858 mol
volume = 0.485 L
molarity = 0.858 / 0.485 = 1.77 M
Ca(OH)2 provides 2 OH- ions
normality = molarity * 2 = 1.77 * 2 = 3.54 N
Correct answer: A
What is the oxidation number of sulfur in H₂SO₄?
What is the oxidation number of iodine in KIO₄?
What's the predicted charge for an oxide ion?
Whats the predicted charge for a calcium ion?
+4
+7
2-
2+
When the equation NH3 + O2 = N2 + H2O is completely balanced, the coefficient of H2O will be:
When the equation NH3 + O2 = N2 + H2O is completely balanced, the coefficient of NH3 will be:
When the equation C2H4 + O2 = CO2 + H2O is completely balanced, the coefficient of the C2H4 will be:
6
4
1
polar or nonpolar and draw the structure
SH2 H2 C2H2 CHOOH
POLAR, NONPOLAR, NONPOLAR, POLAR
Which is an oxidation–reduction reaction?
A. KI = K+ + I–
B. AgNO3 + NaCl = AgCl + NaNO3
C. 3 O2 = 2 O3
D. 4 Na + O2 = 2 Na2O
D
name all the diatomic elements
H O N I F Br Cl
After 3 half-lives, how many grams will remain of a 120 g sample of sodium-24?
Remaining = 120 × (1/2)³
Remaining = 120 × 0.125
Remaining = 15.0