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What is the SI prefix for the factor 10⁻²?

centi- (symbol c).

Give an example of an intensive property.

Any property that does not depend on sample size, e.g., boiling point, density, temperature.

How many significant figures should be recorded when reading 21 mL from a graduated cylinder marked every 1 mL?

Three digits, e.g., 21.2 mL (one estimated digit beyond the smallest marking).

Convert 100.00 °C to kelvins.

373.15 K (add 273.15).

Write the specific-heat equation.

q = m c ΔT (heat = mass × specific heat × temperature change).

State the Law of Definite Proportions.

All samples of a given compound have the same proportion by mass of their constituent elements.

What did Rutherford’s gold-foil experiment reveal about atomic structure?

Atoms possess a tiny, dense, positively charged nucleus containing most of the mass; electrons occupy the surrounding volume.

Which law is used to convert between pressure, volume, moles, and temperature of an ideal gas?

The ideal gas law, PV = nRT.

Define molar mass.

The mass (in grams) of one mole of a substance.

Give the value and meaning of Avogadro’s number.

6.022 × 10²³; the number of particles in one mole.

What is the oxidation state of carbon in CO₃²⁻?

+4.

When is a process considered endothermic?

When the system absorbs heat from the surroundings (e.g., melting ice).

Write the dilution equation relating concentration and volume.

M₁V₁ = M₂V₂.

Define limiting reactant.

The reactant that is completely consumed first, limiting the amount of product formed.

Give the formula for hydrobromic acid.

HBr (aq).

Which compound is ionic: BrF₅, HNO₃, MgSO₄, or NI₃?

MgSO₄ (contains a metal cation and polyatomic anion).

Name the compound Li₃N.

Lithium nitride.

What is the empirical formula for a compound that is 36.86 % N and 63.14 % O by mass?

NO₂.

How is percent yield calculated?

% yield = (actual yield / theoretical yield) × 100 %.

State one rule from Dalton’s atomic theory that is no longer strictly correct.

‘Atoms are indivisible’ (we now know atoms are composed of subatomic particles).

Which pair of elements exhibits the greatest similarity in chemical properties?

Sr and Ba (they are in the same group).

What species has 26 protons, 29 neutrons, and 23 electrons?

Fe³⁺ with mass number 55 (⁵⁵Fe³⁺).

How many electrons are found in Ni²⁺?

26 electrons.

Define an isotope.

Atoms of the same element with different numbers of neutrons (different mass numbers).

Write the combustion products for a hydrocarbon (or alcohol) burned in excess oxygen.

CO₂ and H₂O.

Which solubility rule explains why AgCl precipitates from solution?

Most chlorides are soluble except those of Ag⁺, Pb²⁺, and Hg₂²⁺.

What distinguishes a precipitation reaction?

Formation of an insoluble solid (precipitate) when two aqueous solutions are mixed.

What is the bond angle in a perfect tetrahedral molecule?

Approximately 109.5°.

How many electron groups and lone pairs are around the nitrogen in NH₃?

Four electron groups, one lone pair.

Which element can have an expanded octet, B, F, S, or He?

S (elements in period 3 or higher can exceed an octet).

Give the electron configuration of arsenic (As).

[Ar] 4s² 3d¹⁰ 4p³.

Which region of the electromagnetic spectrum has the longest wavelength listed: X-ray, ultraviolet, infrared, or microwave?

Microwave.

Describe the relationship between photon energy and wavelength.

Energy is inversely proportional to wavelength (E ∝ 1/λ).

What happens to wavelength and energy when an H-atom electron drops from n = 4 to n = 2 versus n = 4 to n = 1?

The n = 4 → 2 photon has a longer wavelength and lower energy than the n = 4 → 1 photon.

State STP conditions for gases.

0 °C (273 K) and 1 atm pressure.

Which element has the highest first ionization energy: In, I, Rb, or Sb?

I (iodine).

Order Sr, Ca, and Se by decreasing atomic radius.

Sr > Ca > Se.

Define molecular polarity.

A molecule is polar if its bond dipoles do not cancel, giving a net dipole moment.

Give the molecular geometry of NCl₃.

Trigonal pyramidal.

Choose a molecule that contains polar bonds but is overall nonpolar.

CO₂ (linear molecule with two equal C=O dipoles that cancel).

Express the ideal-gas constant R in SI units.

0.08206 L · atm · mol⁻¹ · K⁻¹ (or 8.314 J · mol⁻¹ · K⁻¹).

What is the formula mass of CCl₂F₂?

120.9 amu.

How many oxygen atoms are in Fe₂(SO₄)₃?

12 oxygen atoms (3 sulfate ions × 4 O each).

Write the net ionic equation for the reaction of HBr(aq) with NaOH(aq).

H⁺(aq) + OH⁻(aq) → H₂O(l).

How many moles of Br⁻ are present in 0.300 L of 0.150 M AlBr₃?

0.135 mol Br⁻ (0.150 mol/L × 0.300 L × 3 Br⁻ per formula unit).

What equation relates frequency (ν) and wavelength (λ) of light?

c = λν (speed of light = wavelength × frequency).

Explain why melting is endothermic while condensation is exothermic.

Melting requires heat to overcome intermolecular forces; condensation releases heat as molecules form stronger interactions.

Define molarity.

Moles of solute per liter of solution (mol / L).