A scientist obtains a mixture of methane and oxygen in a closed opaque vessel. She knows that a mixture of methane and oxygen is a clear gas. She then follows these steps:Light a fuse to provide a spark inside of the vessel.Carefully extract the gas out the vessel directly into a large sealed test tube.Observe the gas in the test tube.Determine whether or not a chemical reaction occurred after lighting the fuse.The scientist sees that the gas in the test tube is still a clear gas. How can the scientist determine whether or not a chemical reaction occurred in the test tube? A. by observing the color of the gases in the test tube and comparing them to those of methane and oxygen B. by testing the boiling points of the gases in the test tube and comparing them to those of methane and oxygen C. by determining whether or not a phase change occurred because the fuse was sparked D. by determining whether or not mass of matter was gained because the fuse was sparked
Question
A scientist obtains a mixture of methane and oxygen in a closed opaque vessel. She knows that a mixture of methane and oxygen is a clear gas. She then follows these steps:Light a fuse to provide a spark inside of the vessel.Carefully extract the gas out the vessel directly into a large sealed test tube.Observe the gas in the test tube.Determine whether or not a chemical reaction occurred after lighting the fuse.The scientist sees that the gas in the test tube is still a clear gas. How can the scientist determine whether or not a chemical reaction occurred in the test tube? A. by observing the color of the gases in the test tube and comparing them to those of methane and oxygen B. by testing the boiling points of the gases in the test tube and comparing them to those of methane and oxygen C. by determining whether or not a phase change occurred because the fuse was sparked D. by determining whether or not mass of matter was gained because the fuse was sparked
Solution 1
The scientist can determine whether or not a chemical reaction occurred in the test tube by testing the boiling points of the gases in the test tube and comparing them to those of methane and oxygen. This is because a chemical reaction often results in the formation of new substances, which would have different physical properties, such as boiling points, from the original substances. Therefore, if the boiling points of the gases in the test tube are different from those of methane and oxygen, it would suggest that a chemical reaction has occurred.
Solution 2
The scientist can determine whether or not a chemical reaction occurred in the test tube by testing the boiling points of the gases in the test tube and comparing them to those of methane and oxygen. This is because a chemical reaction often results in the formation of new substances, which would have different physical properties, such as boiling points, from the original substances.
The other options are not as reliable. Observing the color of the gases would not be helpful because both methane and oxygen are colorless gases, and many of their possible reaction products are also colorless. Determining whether or not a phase change occurred because the fuse was sparked would not necessarily indicate a chemical reaction, as the spark could simply heat the gases and cause them to expand without reacting. Finally, determining whether or not mass of matter was gained because the fuse was sparked would not be a reliable indicator of a chemical reaction, as the law of conservation of mass states that matter cannot be created or destroyed in a chemical reaction.
Similar Questions
For which of the following cases is there a clear indication that a chemical reaction is taking place?Case 1: Two clear, colorless liquids at 19.5 degrees Celsius are combined in a test tube. A few seconds later, the contents of the test tube appear to be a clear, colorless liquid with a temperature of 19.8 degrees Celsius.Case 2: Two clear, colorless liquids at 24.3 degrees Celsius are combined in a test tube. A few seconds later, the contents of the test tube appear to be a clear, colorless liquid with a temperature of 32.9 degrees Celsius.
According to the pre-lab presentation, which of the following is a reason for a "false positive" conclusion that a chemical reaction occurred in the test tube?Group of answer choicesTwo clear colorless liquids are combined and produce no visual change (still a clear colorless liquid) when the test tube is agitated.Bubbles are observed after the test tube is agitated.An odor is generated when the test tube is agitated.A red color in the test tube changes to a blue color after the test tube is agitated.
A student observes several reactions. Describe one observation the student might make that would indicate a chemical reaction has taken place.
Which of the following is NOT evidence that a chemical reaction has occurred? Group of answer choicescolor change when chemicals are contacted with each othersolid formation when chemicals are contacted with each othergas formation when chemicals are contacted with each otheremission of light when chemicals are contact with each otherAll of the above are evidence of a chemical reaction.
How do you know a chemical reaction has taken place?
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