emperature Control and Chocolate Sculptures

Question

A chocolate artist wants to create small chocolate sculptures that can be purchased as gifts for special occasions. She will create the sculptures in a temperature-controlled room within her chocolate shop. Controlling the temperature of the room is necessary because the visual appearance of chocolate can change if it is heated or cooled outside of a specific temperature range. For example, if the chocolate rises above 18°C, the sculpture may begin to melt and change shape. If the chocolate drops below 15°C, the sculpture may begin to discolor as sugar in the chocolate crystallizes and rises to the surface.

The artist wants to design a box to transport the chocolate sculptures when they are delivered. The chocolate shop is located in a city where the temperatures range between 22°C and 30°C all year long. The temperature inside the delivery van is 20°C. The ideal box will be temperature-controlled using a pack that she will design. The pack will hold a chemical substance and 100 grams of water in separate parts of the pack. Squeezing the pack will combine the two substances, causing a chemical reaction to take place that absorbs or releases energy, depending on the substance. The packs will be activated and added to the insulated box and the chocolate sculpture when it is ready to be transported. The box to transport the chocolate sculptures is shown.

The chocolate artist purchases four different substances: ammonium nitrate, calcium chloride, sodium acetate, and sodium hydroxide. She will test the effects of each substance by adding various amounts to the 100 grams of water, then choose one to create the temperature-control packs. The initial temperature of the water before adding the substance is 20° Celsius. The table shows how much the temperature increased or decreased for each substance. A negative (-) in front of the temperature change indicates a decrease in temperature, and a positive (+) indicates an increase. The artist knows that the kinetic energy of the solution decreases as the temperature decreases.

Substance 10 g 20 g 30 g 40 g 50 g
ammonium nitrate -3 -6 -10 -14 -17
calcium chloride +11 +17 +24 +30 +35
sodium acetate -1 -2 -3 -4 -7
sodium hydroxide +12 +20 +29 +35 +41
Multiple Choice Question
The chocolate artist creates a temperature-control pack to transport her chocolate. She tests the pack while transporting a chocolate sculpture on a very hot day. She finds that the temperature inside of the box is still within the desired range if the trip lasts only one hour. However, if the trip lasts for two hours, the temperature inside of the box is too hot. Which update to the design can the chocolate artist make for longer trips?

A.
She can make a larger temperature-control pack using less of the same chemical.

B.
She can make a smaller temperature-control pack using less of the same chemical.

C.
She can add a second temperature-control pack that is identical to the first pack to the box.

D.
She can add a second temperature-control pack with the coldest possible temperature to the box.

Answer 1

To determine the best update to the design for longer trips, we need to consider the performance of the temperature-control pack over extended periods. Since the initial test showed that the temperature inside the box is within the desired range for one hour but too hot for two hours, the goal is to improve heat absorption for longer durations.

Here's an analysis of the options:

A. She can make a larger temperature-control pack using less of the same chemical.

• Making a larger pack with less of the chemical does not necessarily mean it will be more effective in controlling temperature. It may not absorb as much heat, which would not alleviate the temperature issue for longer trips.

B. She can make a smaller temperature-control pack using less of the same chemical.

• A smaller pack would likely have even less capacity to absorb heat, making it worse for temperature control.

C. She can add a second temperature-control pack that is identical to the first pack to the box.

• Adding a second identical pack should improve heat absorption, as both packs can work together to maintain a cooler temperature for a longer duration.

D. She can add a second temperature-control pack with the coldest possible temperature to the box.

• While this option sounds appealing, if she adds a pack that releases heat instead of absorbing it, it might not help. The focus should be on packs that cool or absorb heat.

Given these considerations, the most effective design update for longer trips would be:

C. She can add a second temperature-control pack that is identical to the first pack to the box.

This would enhance the cooling effect and help maintain the desired temperature for the duration of the trip.