AP chem final short answers

Precision vs. Accuracy

Accuracy is closeness to the true value; precision is closeness between repeated measurements.

Rutherford Experiment

Most alpha particles passed through gold foil, but a few deflected, showing atoms are mostly empty space with a small, dense, positive nucleus.

Limiting reactant pizza question. 250 mL of sauce, 1 crust, and 15 pepperoni slices (with sauce as the LR).

You will need 1L of sauce, more than 4 crusts, and 60 pepperonis to make 4 pizzas when the sauce runs out first.

Weak vs strong vs nonelectrolytes compare and contrast

Strong electrolytes form ions and conduct electricity well, Weak electrolytes partially form ions and conduct electricity weakly, while nonelectrolytes does not form ions or conduct electricity. Both describe how substances form ions in water and conduct electricity

Kinetic Molecular Theory (KMT)

Gas particles move constantly and randomly, have negligible volume, experience no significant intermolecular forces, and undergo elastic collisions. Their average kinetic energy is directly proportional to their Kelvin temperature.

Gas Stoichiometry at and Not at STP

At STP (273 K and 1 atm), one mole of ideal gas occupies about 22.4 L. At other conditions, use PV=nRT to find moles or volume, then use the balanced equation's mole ratio to convert between substances.

Real vs. Ideal Gases compare and contrast

Both describe the behavior of gas particles, which move randomly and collide with each other and their container. Ideal gases have negligible particle volume and no intermolecular forces, while real gases have both. Real gases behave most ideally at high temperatures and low pressures.

Nature of Energy

Energy is the ability to do work or transfer heat. It can change forms, but total energy is conserved in an isolated system.

State Functions

State functions depend only on initial and final states, not the path. Examples include enthalpy, pressure, volume, and temperature; heat and work are not state functions.

Hess's Law

Total Delta H equals the sum of reaction-step enthalpies. Reversing an equation reverses its Delta H sign; multiplying an equation multiplies its Delta H by the same factor.