Bag Lab 5.15.12
An endothermic reaction is one in which energy is absorbed, resulting in a decrease in temperature.
An exothermic reaction is one of which energy is released, resulting in an increase in temperature.
An exothermic reaction is one of which energy is released, resulting in an increase in temperature.
1. How do the results of each reaction compare with your predictions for that reaction?
My first prediction was completely wrong; no bubbles were produced. The reaction had changed color, and it was cold. Then, my second prediction was correct; there was fizzing and a gas was released. Though the reaction changes color and became warm.
2. What was/were the observable chemical indicators that led you to believe a chemical reaction occurred when you mixed the sodium bicarbonate and indicator solution #1?
The color changed and the reaction became cold.
3. What was/were the observable chemical indicators that led you to believe a chemical reaction occurred when you mixed the sodium bicarbonate and indicator solution and calcium chloride #2?
The color changed to a yellow, a gas was released, bubbles formed, and the reaction became warm.
4. Gas formation is one possible indicator of a chemical change. Is there ever an instance when gas formation could indicate a physical change in a substance rather than a chemical change? EXPLAIN your answer. Yes/No is not adequate.
Boiling water is an example of a physical change. The gas released is still water, just in a different state.
5. The temperature of two seperate solutions is found to be 20 degrees C. When the solutions are mixed, a precipitate forms and the temperature changes to 18 degrees C. Classify the type of change in energy and explain your answer.
It was an endothermic reaction. There was a chemical change and the substances' temperature dropped as the two substances were mixed.
My first prediction was completely wrong; no bubbles were produced. The reaction had changed color, and it was cold. Then, my second prediction was correct; there was fizzing and a gas was released. Though the reaction changes color and became warm.
2. What was/were the observable chemical indicators that led you to believe a chemical reaction occurred when you mixed the sodium bicarbonate and indicator solution #1?
The color changed and the reaction became cold.
3. What was/were the observable chemical indicators that led you to believe a chemical reaction occurred when you mixed the sodium bicarbonate and indicator solution and calcium chloride #2?
The color changed to a yellow, a gas was released, bubbles formed, and the reaction became warm.
4. Gas formation is one possible indicator of a chemical change. Is there ever an instance when gas formation could indicate a physical change in a substance rather than a chemical change? EXPLAIN your answer. Yes/No is not adequate.
Boiling water is an example of a physical change. The gas released is still water, just in a different state.
5. The temperature of two seperate solutions is found to be 20 degrees C. When the solutions are mixed, a precipitate forms and the temperature changes to 18 degrees C. Classify the type of change in energy and explain your answer.
It was an endothermic reaction. There was a chemical change and the substances' temperature dropped as the two substances were mixed.