Kuwait University Chemistry Aptitude Test flashcards

31 cards. Read the term and the definition here. The deck at the top of this page is optional.

Subject–verb agreement

A verb must match its subject in number. Prepositional phrases between subject and verb do not change the number, so 'the box of pens is' remains singular.

Comma splice

Two independent clauses joined by only a comma. It is corrected with a period, a semicolon, or a comma plus coordinating conjunction such as 'but'.

Dangling modifier

An introductory phrase that does not logically describe the subject of the main clause, as in 'Having finished the exam, the door opened'.

Restrictive versus non-restrictive clause

A restrictive clause carries essential information and takes 'that' with no commas. A non-restrictive clause adds extra information and takes 'which' with commas.

Affect versus effect

'Affect' is normally a verb meaning to influence. 'Effect' is normally a noun meaning a result, though it can be a verb meaning to bring about.

Inference versus implication

A writer or speaker implies a meaning indirectly; a reader or listener infers it. Main-idea questions test what the whole passage implies.

Parallel structure

Items joined by 'and', 'or', or 'but' must share the same grammatical form, such as three gerunds or three infinitives, not a mixture.

Quadratic formula

x equals negative b plus or minus the square root of b squared minus four ac, all divided by two a, used to solve ax² + bx + c = 0.

Discriminant

The value b² − 4ac in a quadratic equation. Positive gives two real roots, zero gives one repeated root, negative gives no real roots.

Perpendicular slope rule

Two non-vertical lines are perpendicular exactly when the product of their slopes equals negative one, so a slope of 2 pairs with −1/2.

Logarithm product rule

The logarithm of a product equals the sum of the logarithms: log(ab) = log a + log b, valid for positive a and b in any common base.

Arithmetic sequence sum

For an arithmetic sequence, the nth term is a₁ + (n − 1)d and the sum of n terms is n times the average of first and last terms.

Pythagorean identity

For any angle θ, sin²θ + cos²θ = 1. Dividing by cos²θ gives 1 + tan²θ = sec²θ, a frequent simplification tool.

Independent events probability

When events do not influence each other, the probability that both occur is the product of their separate probabilities.

Derivative power rule

The derivative of x to the power n is n times x to the power n minus one, for any real constant n.

Mole concept

One mole of a substance contains 6.022 × 10²³ particles and has a mass in grams equal to its molar mass.

Molarity

Molarity is moles of solute divided by liters of solution. On dilution the moles stay constant, so M₁V₁ = M₂V₂.

pH scale

pH equals the negative logarithm of the hydronium ion concentration. At 25 °C, pH below 7 is acidic, 7 neutral, above 7 basic.

Oxidation and reduction

Oxidation is loss of electrons and an increase in oxidation number. Reduction is gain of electrons and a decrease in oxidation number.

Le Chatelier's principle

A system at equilibrium shifts to oppose a disturbance: adding reactant shifts forward, raising pressure favors fewer gas moles, heating favors the endothermic direction.

Ideal gas law

PV = nRT relates pressure, volume, moles, and absolute temperature. With R = 0.0821 L·atm/(mol·K), temperature must be in kelvin.

Polar versus nonpolar molecule

Polar bonds may cancel by symmetry. Carbon dioxide has polar bonds but is nonpolar; water's bent shape leaves a net dipole.

Strong versus weak acid

A strong acid ionizes completely in water, such as HCl or HNO₃. A weak acid ionizes only partly and needs its Ka to find pH.

Newton's second law

The net force on an object equals its mass times its acceleration, F = ma. Weight is the special case W = mg.

Kinematic equations

For constant acceleration: v = u + at, s = ut + ½at², and v² = u² + 2as. They fail when acceleration changes.

Conservation of momentum

If no external net force acts, total momentum before a collision equals total momentum after: m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂.

Ohm's law

Current through a conductor is proportional to the potential difference across it: V = IR, where R is resistance in ohms.

Electrical power formulas

Power dissipated in a circuit equals VI, or I²R, or V²/R. The unit is the watt, equal to one joule per second.

Wave equation

Wave speed equals frequency times wavelength, v = fλ. Frequency is fixed by the source; wavelength changes with the medium.

Snell's law

n₁ sin θ₁ = n₂ sin θ₂ describes refraction at a boundary, where n is the refractive index and angles are measured from the normal.

Kinetic energy and temperature

For an ideal gas, average molecular kinetic energy is proportional to absolute temperature, so doubling kelvin temperature doubles average kinetic energy.