Random 1
In the following oxidation-reduction reactions, what element is oxidized and what element is reduced? 3CoSO4 + 5 KI + KIO3 + 3 H2O --> 3Co(OH)2 + 3K2SO4 + 3 I2
I in KI is oxidized and
I in IO3 is reduced
Name it: Na₂SO₄ • 10H₂O
Sodium sulfate decahydrate
8Al + 3Fe₃O₄ → 9Fe + 4Al₂O₃
In the reaction above, how many moles of Aluminum will produce 1.0 mol of Iron?
8/9 or 0.89
Provide the correct formula for: ammonium oxalate
(NH₄)₂C₂O₄
A sample of a solid metal has a mass of 23.795 g. When placed in a graduated cylinder with 55.25 mL of water, the water level rises to 61.00 mL. What is the density of the metal (3 SF)?
4.14 g/cm³
Antimony, Sb, has two stable isotopes. Given that 43.8% of natural antimony is Sb-123 with the experimentally determined mass of 122.904 amu, what is the other stable isotope?
Sb - 121
Write the balanced molecular reaction (include states): Magnesium carbonate solution plus aqueous hydrochloric acid.
MgCO₃(aq) + 2HCl(aq) → MgCl₂(aq) + H₂O(l) + CO₂(g)
2MnO₄⁻ + 5H₂O₂ + 6H⁺ → 2Mn²⁺ + 8H₂O + 5O₂
What volume of 0.150 M KMnO₄ is needed to titrate 75.0 mL of 0.150 M H₂O₂?
30.0 mL
How many grams of HNO₃ can be prepared from the reaction of 138 g NO₂ with 54.0 g H₂O?
3NO₂ + H₂O → 2HNO₃ + NO
126g HNO3
Perform the operation with correct sig figs:
(3.8095 × 6.02214 × 10²³) ÷ (39.0983 + 15.9994 + 1.00794)
4.0890 × 10²²
A 16.8-g mineral sample produced 4.4-g CO₂ when dissolved in acid. If only MgCO₃ is present, what % MgCO₃ by mass is in the sample?
(MM: MgCO₃ = 84; CO₂ = 44)
50%
A 4.60 L bulb filled with gas at 1.80 atm and 22.0°C gained 9.50 g. Identify the gas.
N2
100.0 mL of dichromate ions (unknown M) were titrated with 0.100 M FeCl₂; 43.2 mL were used. Find the dichromate molarity.
0.00720 M Cr₂O₇²⁻
Provide the net-ionic equation: Sodium sulfide + lead(II) nitrate
S²⁻(aq) + Pb²⁺(aq) → PbS(s)
MnO₄⁻ + Fe²⁺ → Fe³⁺ + Mn²⁺ (acidic solution)
A 50.00 mL Fe²⁺ solution requires 36.43 mL of 0.025 M KMnO₄ for full reaction. What is [Fe²⁺]?
9.1 × 10⁻² M
Ethanoic acid solution is added to sodium hydrogen carbonate. Include states. Determine the net ionic equation.
HC₂H₃O₂(aq) + HCO₃⁻(aq) → CO₂(g) + H₂O(l) + C₂H₃O₂⁻(aq)
An element X forms XCl₂ and XCl₄. 10.00 g XCl₂ + excess Cl₂ → 12.55 g XCl₄. Calculate the atomic mass of X and identify it.
207.2 g/mol (Lead)
The Earth’s crust contains 4.0 g U per metric ton. What mass of U (kg) could be extracted from 1500 lb of crust?
2.7 × 10⁻³ kg U
25.0 mL 0.250 M KI, 25.0 mL 0.100 M K₂SO₄, and 15.0 mL 0.100 M MgCl₂ are mixed. Find molar concentrations of I⁻, Cl⁻, and K⁺.
I⁻: 0.0962 M
Cl⁻: 0.0462 M
K⁺: 0.173 M
A gas sample is 40.1% S and 59.9% O. Measured: P = 1.00 atm; V = 500.0 mL; T = 298 K; mass = 1.635 g. Determine the molecular formula.
SO₃
Balance in basic conditions:
Co(OH)₃(aq) + Sn(s) → Co(OH)₂(aq) + HSnO₂⁻(aq)
OH⁻ + 2Co(OH)₃ + Sn → 2Co(OH)₂ + HSnO₂⁻ + H₂O
NaN₃(s) → Na(s) + N₂(g).
65.1 L N₂ needed; density = 0.916 g/L.
a) How many grams NaN₃ are needed?
b) How much Fe₂O₃ must be added to react with Na?
a) 92.2 g NaN₃
b) 37.7 g Fe₂O₃
A 525 cm² iron sheet is covered with 0.0021 cm rust (Fe₂O₃, ρ = 5.2 g/cm³). What minimum volume (mL) of 14% HCl (ρ = 1.07 g/mL) is required to clean the rust?
52.34 mL
Q24: Lake Waco water contains 0.9 µg Hg/cm³. Volume = 9.7 × 10⁷ m³. Find total Hg mass in kg.
8.7 × 10⁴ kg Hg
Combustion of octane:
2C₈H₁₈ + 25O₂ → 16CO₂ + 18H₂O
Cylinder volume = 0.500 L, 45.0°C, 1.00 atm, air is 20% O₂. How many grams of octane are needed?
0.0350 g