Question

an advertisement for a commercial hand warmer claims that the hand warmer works because a chemical reaction in the hand warmer draws out the body’s own natural heat, causing a warming effect. which of the following states the accuracy of the claim in the advertisement and best provides a correct scientific justification of the claim?

a the advertisement’s claim is inaccurate because heat flowing from the hands to the warmer would only happen if the chemical reaction was endothermic, which would cause the hands to feel colder.

b the advertisement’s claim is inaccurate because heat flowing from the hands to the warmer would only happen if the chemical reaction was exothermic, which would cause the hands to feel colder.

c the advertisement’s claim is accurate because heat flowing from the hands to the warmer would only happen if the chemical reaction was endothermic, which would cause the hands to feel warmer.

d the advertisement’s claim is accurate because heat flowing from the hands to the warmer would only happen if the chemical reaction was exothermic, which would cause the hands to feel warmer.

Explanation:

To determine the accuracy of the hand warmer advertisement's claim, we analyze heat transfer and reaction types:

1. Endothermic vs. Exothermic Reactions:

• An endothermic reaction absorbs heat from the surroundings.
• An exothermic reaction releases heat to the surroundings.

1. Heat Transfer Direction: Heat flows from a warmer object to a cooler object.
2. Analyzing the Claim: The advertisement says the reaction “draws out the body’s natural heat” (heat flows from hands to the warmer). For heat to flow from hands to the warmer, the warmer must be cooler than the hands. This would occur if the reaction is endothermic (absorbing heat from hands, making the warmer cooler initially, so heat flows from hands to warmer). However, if the reaction is endothermic, absorbing heat from the hands would make the hands feel colder (not warmer), so the advertisement’s claim (that this causes a “warming effect”) is inaccurate.
3. Evaluating Options:

• Option A: Correctly states the claim is inaccurate. It explains that heat flowing from hands to the warmer requires an endothermic reaction, which would make hands feel colder (matching our analysis).
• Option B: Incorrectly associates heat flow from hands to warmer with an exothermic reaction (exothermic reactions release heat, so the warmer would be warmer than hands, and heat would not flow from hands to warmer).
• Options C and D: Incorrectly claim the advertisement’s claim is accurate (the end result of an endothermic reaction drawing heat from hands is cold hands, not a warming effect).

Answer:

A. The advertisement’s claim is inaccurate because heat flowing from the hands to the warmer would only happen if the chemical reaction was endothermic, which would cause the hands to feel colder.