Hi guys,
need help with homework...got some done, but not sure about these thanks for any help! :)
Take a balloon filled with hydrogen gas. Touch a match
to the balloon. What happens? Big boom and lots of heat
given off. Is ΔH favorable or unfavorable?? It would be favorable as its going out to the environment, right?
Add solid urea to a beaker of water. The beaker gets very cold.
Is ΔH favorable or unfavorable???
Unfavorable as there would be no net heat lost, right?
To determine whether ΔH (enthalpy change) is favorable or unfavorable in these scenarios, we need to understand the concept of exothermic and endothermic reactions.
1. Igniting a hydrogen-filled balloon:
When you touch a match to a hydrogen-filled balloon, the hydrogen gas reacts with oxygen in the air to produce water vapor. This is a highly exothermic reaction, meaning it releases heat. In this case, ΔH is negative, indicating that heat is released to the surroundings. Therefore, the ΔH is favorable, as heat is given off.
2. Adding solid urea to water:
When solid urea is added to water, the urea dissolves and forms a solution. This process is usually endothermic, meaning it absorbs heat from the surroundings. As a result, the beaker containing the water and urea mixture feels cold. In this case, ΔH is positive, indicating that heat is absorbed from the surroundings. Therefore, the ΔH is unfavorable, as heat is absorbed.
So, to answer your questions:
1. ΔH for igniting a hydrogen-filled balloon is favorable or negative because heat is released.
2. ΔH for adding solid urea to water is unfavorable or positive because heat is absorbed.