IBSL Chemistry Topic 6 Kinematics Multiple Choice Questions

Both the energy of molecules and the orientation of the molecules are important in determining whether a reaction occurs. The energy of molecules is crucial because a certain amount of energy is required to break the existing bonds and form new ones. If the energy of the molecules is not sufficient, the reaction may not occur. Additionally, the orientation of the molecules is important because the reactant molecules need to collide in the correct orientation in order for the reaction to take place. If the molecules collide in an incorrect orientation, the reaction may not occur. Therefore, both factors are important in determining whether a reaction occurs.

Both the energy of the molecules and the orientation of the molecules are important in determining whether a reaction occurs. The energy of the molecules determines if they have enough energy to overcome the activation energy barrier and initiate the reaction. The orientation of the molecules is important because for a reaction to occur, the molecules must collide in a specific orientation that allows the necessary bonds to be broken and formed. Therefore, both factors are necessary for a reaction to take place.

Increasing the activation energy does not increase the rate of a reaction. Activation energy is the minimum energy required for a reaction to occur. By increasing the activation energy, it becomes more difficult for the reactants to reach the required energy level, thus slowing down the reaction rate. Therefore, increasing the activation energy does not contribute to increasing the rate of a reaction.

The correct answer is that the molecules do not have enough energy. This is because for a reaction to occur, the reactant molecules must collide with sufficient energy to overcome the activation energy barrier. If the molecules do not have enough energy, the collision will not result in the formation of products. The other options, such as the molecules not colliding in the proper ratio, low concentration, or being at equilibrium, do not directly relate to the energy required for a successful reaction.

The rate of reaction between magnesium and HCl increases with an increase in concentration of HCl and temperature. In this case, the highest concentration of HCl is 2.0 mol dm-3 and the highest temperature is 35oC, so the rate of reaction will be fastest under these conditions.

The concentration of the hydrochloric acid affects the rate of reaction. A higher concentration of HCl (2 mol dm-3) will result in a faster rate of reaction compared to a lower concentration (1 mol dm-3). Additionally, using CaCO3 powder instead of pieces will also increase the rate of reaction. This is because a larger surface area is exposed to the acid when using powder, allowing for more collisions between the reactant particles and increasing the rate of reaction.

The correct answer is that the molecules do not have enough energy. In order for a reaction to occur, the molecules must collide with enough energy to overcome the activation energy barrier. If the molecules do not have enough energy, they will not be able to break the existing bonds and form new ones to create products. The other options, such as the molecules not colliding in the proper ratio or the concentration being too low, may also affect the reaction rate, but the lack of energy is the most likely reason for the lack of product formation.

The statement "Very few nitrogen and oxygen molecules have sufficient energy to react" best explains why the reaction between nitrogen and oxygen in the atmosphere under normal conditions is extremely slow. This suggests that the majority of nitrogen and oxygen molecules do not possess the necessary energy to overcome the activation energy barrier and initiate a reaction.

When the concentration of the reactants increases, there are more molecules available to collide with each other. This leads to an increase in the frequency of molecular collisions, which in turn increases the rate of the reaction. As more collisions occur, there is a higher probability of successful collisions that lead to the formation of products. Therefore, the increase in the frequency of molecular collisions is the most likely reason for the increase in the rate of the reaction.

The addition of a catalyst to a chemical reaction alters the rate primarily by providing a different reaction pathway. A catalyst works by lowering the activation energy required for the reaction to occur, allowing the reaction to proceed more quickly. It does this by providing an alternative pathway with a lower activation energy, which allows more reactant molecules to overcome the energy barrier and react. This increases the rate of the reaction by increasing the number of successful collisions between reactant molecules.

In this question, the rate of reaction is determined by the concentration of the HCl solution and the temperature. Increasing the concentration of the HCl solution will increase the rate of reaction because there are more HCl particles available to react with the magnesium. Additionally, increasing the temperature will also increase the rate of reaction because it provides more energy for the particles to collide and react. Therefore, the case where both new conditions contribute to an increase in the rate of reaction is when there is 50 cm3 of 1.2 mol dm-3 HCl at 30 C.

The rate of a reaction is defined as the change in concentration of a reactant or product per unit time. Therefore, the units used for a rate are typically expressed in terms of concentration (mol dm-3) divided by time (s, min, etc.), which gives the rate of reaction as mol dm-3 time-1.

The graph shows a decrease in the concentration of the acid over time, indicating that it is being consumed in the reaction. This suggests that the acid is reacting with the calcium carbonate to form a product, causing the concentration of the acid to decrease. The other options cannot be deduced from the information given in the question.

Increasing the Fe3+ ion concentration will increase the rate of the reaction because there will be more Fe3+ ions available to react with the tin metal. This will increase the frequency of successful collisions between the reactant particles and therefore increase the rate of the reaction. Decreasing the size of the tin pieces will also increase the rate of the reaction because it will increase the surface area of the tin metal available for reaction. This will increase the number of active sites for the reaction to occur, leading to an increase in the rate of the reaction.

The rate of the reaction shown will be influenced by the number of collisions per second, the energy of the collisions, and the geometry with which the molecules collide. The number of collisions per second is important because a higher collision frequency increases the chances of successful collisions. The energy of the collisions is crucial because it determines whether the collisions have enough energy to overcome the activation energy barrier and proceed with the reaction. The geometry with which the molecules collide is significant because it affects the orientation of the reactant molecules during collision, which can impact the reaction rate.

In this question, the rate of reaction is being measured for the reaction between magnesium and hydrochloric acid. Generally, an increase in the concentration of the reactants or an increase in temperature leads to an increase in the rate of reaction.

Among the given options, the condition that would contribute to an increase in the rate of reaction is "50 cm3 of 1.2 mol dm-3 HCl at 30° C". This is because the concentration of HCl is higher (1.2 mol dm-3) compared to the other options, and the temperature is also higher (30° C) compared to the initial condition (25° C). Both of these factors would increase the rate of reaction.

When the temperature is increased, the rate of reaction between two gases increases because it leads to an increase in collision frequency. This is because the higher temperature causes the gas molecules to move faster, resulting in more frequent collisions. On the other hand, adding a catalyst decreases the activation energy required for the reaction to occur. A catalyst provides an alternative pathway for the reaction with a lower activation energy, allowing the reaction to occur more easily. Therefore, the correct statement is that increasing temperature does not change the activation energy and adding a catalyst decreases the activation energy.

By decreasing the size of the CaCO3 solid particles, the surface area of the particles is increased. This allows for more contact between the CaCO3 and the HCl, increasing the frequency of successful collisions and therefore increasing the rate of the reaction. Increasing the pressure of the CO2 would not affect the rate of the reaction as it is a gas and does not directly interact with the solid CaCO3 or the HCl.

The correct answer is that the rate decreases with time because the acid becomes more dilute. This is because as the reaction progresses, the hydrochloric acid is consumed and its concentration decreases. Since the rate of a reaction is directly proportional to the concentration of the reactants, a decrease in acid concentration leads to a decrease in the reaction rate. The size of the calcium carbonate particles is not mentioned in the question and therefore cannot be the main reason for the change in reaction rate.

The catalyst used in the commercial manufacture of ammonia increases the rates of both the forward and reverse reactions. This means that it speeds up the conversion of reactants into products (forward reaction) and also the conversion of products back into reactants (reverse reaction). The catalyst does not have an effect on the position of equilibrium or the yield of ammonia.

Increasing the concentration of HCl will speed up the reaction because it provides more HCl particles for collision with CaCO3, increasing the frequency of successful collisions. Increasing the temperature will also speed up the reaction because it increases the kinetic energy of the particles, leading to more frequent and energetic collisions. However, the size of the CaCO3 particles does not affect the speed of the reaction as it does not change the concentration or kinetic energy of the reactants.

The mass of the flask and contents can be used to measure the rate of the reaction because as the reaction progresses, carbon dioxide gas is produced and escapes from the open flask, resulting in a decrease in the mass of the flask and contents. The pH of the reaction mixture can also be used to measure the rate of the reaction because as the reaction proceeds, hydrochloric acid is consumed and the pH of the mixture will change. Finally, the volume of carbon dioxide produced can be used to measure the rate of the reaction because as the reaction proceeds, more carbon dioxide gas will be produced.

As the temperature of a reaction between two gases is increased, the kinetic energy of the molecules also increases. This leads to a higher fraction of molecules having the energy required to overcome the activation energy barrier and react. Therefore, the rate of the reaction increases. The other options (increased concentrations, increased collisions, and increased pressure) may also have an effect on the reaction rate, but the most significant factor in this case is the increase in the fraction of molecules with sufficient energy.

Diluting the solution would increase the time required for the appearance of sulfur. This is because diluting the solution decreases the concentration of sodium thiosulfate and acid, which in turn slows down the reaction rate. As a result, it takes longer for the reactants to come into contact and form the solid sulfur product.

Neither statement I nor statement II is correct. In a chemical reaction, not every collision between N2 and H2 molecules will produce NH3. The reaction requires the collision between one N2 molecule and three H2 molecules, which is stated incorrectly in statement II. Therefore, the correct answer is Neither I nor II.