#1
Which of the following is a characteristic of a chemical reaction?
Change in color
ExplanationIndication of a chemical change.
#2
What is the role of an acid in a chemical reaction?
To donate protons
ExplanationAcids contribute protons to the reaction medium.
#3
Which of the following is a chemical property?
Reactivity
ExplanationInherent behavior indicating how a substance undergoes reactions.
#4
Which of the following is a characteristic of a reversible reaction?
It can proceed in both forward and reverse directions
ExplanationCapability to undergo forward and reverse processes.
#5
What is the unit of concentration typically used for solutions?
Molarity
ExplanationConcentration measure expressed in moles per liter of solution.
#6
What is the purpose of a catalyst in a chemical reaction?
To provide an alternative reaction pathway with lower activation energy
ExplanationEnabling a faster reaction route with lower energy requirements.
#7
What is the balanced equation for the reaction between sodium hydroxide (NaOH) and hydrochloric acid (HCl)?
NaOH + 2HCl → NaCl + H2O
ExplanationBalanced representation of the neutralization reaction.
#8
What is the role of a catalyst in a chemical reaction?
To increase the rate of reaction
ExplanationFacilitates a faster reaction without being consumed.
#9
In the reaction: 2H2(g) + O2(g) → 2H2O(g), what is the limiting reactant when 3 moles of H2 and 2 moles of O2 are reacted?
O2
ExplanationReactant exhausted first, determining reaction extent.
#10
What is the principle behind the process of fractional distillation?
Fractionation
ExplanationSeparation based on differences in component volatility.
#11
Which statement about catalysts is true?
They provide an alternative reaction pathway with lower activation energy
ExplanationCatalysts lower the energy barrier for reactions.
#12
What does the term 'dynamic equilibrium' refer to in a chemical reaction?
The rate of the forward reaction is equal to the rate of the reverse reaction
ExplanationBalanced rates, though concentrations may change.
#13
According to Le Chatelier's principle, what happens to a system at equilibrium when there is an increase in pressure?
The equilibrium shifts to the side with fewer moles of gas
ExplanationShift in equilibrium to minimize impact of pressure change.
#14
What is the equilibrium constant expression (Kc) for the reaction: N2(g) + 3H2(g) ⇌ 2NH3(g)?
[NH3]^2 / [N2][H2]^3
ExplanationMathematical representation of equilibrium concentrations.
#15
What is the effect of increasing the temperature on an endothermic reaction at equilibrium?
The equilibrium shifts to favor the products
ExplanationHeat absorption favors the endothermic direction.
#16
What is the effect of adding a catalyst to a reaction at equilibrium?
It has no effect on the equilibrium position
ExplanationCatalyst doesn't alter the equilibrium distribution.
#17
What is the effect of increasing the concentration of reactants on the rate of a reaction?
It increases the rate
ExplanationHigher reactant concentration accelerates the reaction.
#18
What is the function of a buffer solution?
To resist changes in pH
ExplanationBuffers maintain stable pH by resisting changes.