physical I (p1& 2) Flashcards
What is the definition of relative atomic mass (Ar)?
The relative atomic mass (Ar) of an element is the average mass of an atom of an element, compared to one-twelfth of the mass of an atom of carbon-12.
What is the ideal gas equation?
PV=nRT
What is the difference between an exothermic and an endothermic reaction?
- Exothermic reaction: Releases energy to the surroundings, usually as heat. (e.g., combustion, respiration)
- Endothermic reaction: Absorbs energy from the surroundings, usually as heat. (e.g., photosynthesis, thermal decomposition)
How is the rate of reaction defined?
The rate of reaction is the change in the concentration of a reactant or product per unit time. It can be measured in terms of the speed at which reactants are used up or products are formed.
What factors affect the rate of reaction?
- Temperature: Increasing temperature increases the rate.
- Concentration: Increasing the concentration of reactants increases the rate.
- Surface area: A larger surface area increases the rate.
- Catalysts: Catalysts increase the rate without being consumed in the reaction.
What is meant by activation energy?
Activation energy is the minimum energy required for reactants to collide with enough energy to react and form products.
What are the properties of ionic compounds?
- High melting and boiling points due to strong electrostatic forces.
- They conduct electricity when molten or in solution.
- They are usually soluble in water.
What is an acid and a base according to the Arrhenius theory?
- Acid: A substance that increases the concentration of hydrogen ions (H⁺) in solution.
- Base: A substance that increases the concentration of hydroxide ions (OH⁻) in solution.
What is pH?
pH is a measure of the acidity or alkalinity of a solution. It is calculated as the negative logarithm of the concentration of hydrogen ions:
pH=−log[H+]
What happens in a neutralization reaction?
HCl (aq)+NaOH (aq)→NaCl (aq)+H2O
Acid + base → salt + water
What is the process of distillation?
Distillation is a method of separating mixtures based on differences in boiling points. It involves heating the mixture to vaporize the component with the lower boiling point, then condensing the vapor back into liquid.
What is the difference between oxidation and reduction in terms of electron transfer?
- Oxidation: The loss of electrons.
- Reduction: The gain of electrons.
What is meant by dynamic equilibrium?
Dynamic equilibrium occurs in a reversible reaction when the rate of the forward reaction equals the rate of the reverse reaction, so the concentrations of reactants and products remain constant over time.
What is Le Chatelier’s Principle?
Le Chatelier’s Principle states that if a system at equilibrium is disturbed by a change in temperature, pressure, or concentration, the system will shift to counteract the disturbance and restore equilibrium.
What is a mole in chemistry?
A mole is the amount of substance that contains exactly 6.022×10^23 entities (atoms, molecules, or ions). This number is known as Avogadro’s number.
What is the difference between a strong acid and a weak acid?
- Strong acid: Fully dissociates in water, releasing all its hydrogen ions (e.g., hydrochloric acid).
- Weak acid: Only partially dissociates in water, releasing some hydrogen ions (e.g., acetic acid).
What is the purpose of titration in chemistry?
Titration is a technique used to determine the concentration of an unknown solution by reacting it with a solution of known concentration.
What is the formula for calculating the energy change in a reaction?
ΔH=Energy of products−Energy of reactants
What is the difference between a saturated and an unsaturated solution?
- Saturated solution: A solution in which no more solute can dissolve at a given temperature.
- Unsaturated solution: A solution in which more solute can dissolve at a given temperature.
What is the rate of reaction?
The rate of reaction is the change in concentration of reactants or products per unit time. It is usually expressed in mol/dm³/s.
What is a rate equation?
A rate equation shows the relationship between the rate of reaction and the concentration of reactants. It is in the form:
Rate=k[A]^a [B] ^b
Where: k is the rate constant
[A] and [B] are the concentrations of reactants
a and b are the orders of reaction with respect to A and B.
What does the order of reaction tell you?
The order of reaction indicates how the rate of reaction is affected by the concentration of a reactant. It can be:
o Zero order: rate is independent of concentration.
o First order: rate is directly proportional to concentration.
o Second order: rate is proportional to the square of concentration.
What is the rate constant k?
The rate constant is a proportionality constant that links the rate of reaction to the concentrations of reactants. It is specific to a particular reaction at a given temperature.
What factors affect the rate of reaction?
The rate of reaction can be influenced by:
1. Concentration of reactants
2. Temperature
3. Surface area of solid reactants
4. Presence of a catalyst