The collision between two gas molecules with different masses results in the velocity of the first molecule decreasing by 1/4. if the collision is elastic, which of the following statements is true? a. the velocity of the second molecule will increase by a factor of 4. b. the velocity of the second molecule will increase by a factor of 16. c. the velocity of the second molecule will decrease by a factor of 16. d. the velocity change of the second molecule depends on both the mass and the velocity of the first molecule. explain why it is the right answer too

The correct option is D.

Explanation: We are given two gas molecules with different masses. The collision between them is elastic, hence the Total Kinetic energy of the system is conserved.

Initial Kinetic Energy:

Final Kinetic Energy:

where,

= mass of first molecule

= mass of second molecule

= initial velocity of first molecule

= initial velocity of second molecule

= final velocity of first molecule

= final velocity of second molecule

Elastic Collision:

That is,

    .....(1)

We are given in the question that the final velocity of first molecule is decreased by 1/4, which means:

Putting this value in equation 1 , we get

taking on other side, we get

From the above relation, it is visible that the velocity change of the second molecule depends on both mass and velocity of the first molecule.

answer: the enthalpy of the overall chemical reaction is +87.88 kj or +88 kj.

according to hess's law, the overall enthalpy of a reaction is the difference between the sum of enthalpy values of all the products and the sum of enthalpy values of all the reactants.

δh(reaction) = ∑nδh(products) - ∑nδh(reactants)

δh(reaction) = [δh +δh] - [δh]

δh(reaction) = [1(-287.02) + 1(0) ] - [1(-374.9)] kj = +87.88 kj

here, δh (pcl3) = -287.02 kj, δh(cl2) = 0, δh(pcl5) = -374.9 kj

therefore, enthalpy of the overall reaction is +87.88 kj or +88 kj.

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.