Question

As part of an investigation into the strength of electrostatic forces between molecules of water, a student will measure the melting point temperature. Which part of the experimental design does this describe?(1 point)
determining the procedure
determining what data to collect
deciding on the appropriate equipment
deciding on the number of trials to perform


Which experimental design would be best to use in investigating the boiling points of water and ethanol?

Heat samples of water and ethanol in two separate beakers using a Bunsen burner. Measure the temperatures at which the samples boil using a thermometer. Record these temperatures as the boiling points.
Mix samples of water and ethanol in a beaker, then heat using a Bunsen burner. Measure the temperature at which the sample boils using a thermometer. Record this temperature as the boiling point.
Heat samples of water and ethanol in two separate beakers using a Bunsen burner. Measure the temperatures at which the samples boil using a thermometer. Conduct several trials and record the average temperatures as the boiling points.
Mix samples of water and ethanol in a beaker, then heat using a Bunsen burner. Measure the temperature at which the sample boils using a thermometer. Conduct several trials and record the average temperature as the boiling point.

Which change happens when a substance melts?(1 point)
The vibration of the molecules produces enough heat to weaken the forces of attraction between the molecules of the substance.
Heat energy overcomes the forces of attraction between the molecules of the substance, so the molecules can move more freely.
Heat energy forces the molecules of the substance farther apart until the rigid structure of the solid breaks.
The molecules of the substance move farther apart, which pulls on the intermolecular bonds between them.
Which change occurs to cause water to boil into steam?(1 point)

The addition of kinetic energy causes the motion of water molecules to overcome gravitational forces.
The addition of kinetic energy causes the motion of water molecules to overcome gravitational forces.
The removal of kinetic energy causes the motion of water molecules to overcome electrostatic forces.
The removal of thermal energy causes the motion of water molecules to overcome gravitational forces.

Answer 1

In an experiment it is known what quantity has to measured, thus the measurement of melting point has been determining what data to collect. Thus, Option B is correct.

To investigate the boiling point of water and ethanol, the samples has to boiled at constant parameters and the data has been collected with several trials. Thus, option C is correct.

Melting has been described as the change of the solid to the liquid state. With melting, there has been heat energy higher than the force of attraction allowing the molecules to move freely. Thus, option B is correct.

The boiling has been the change in the water at liquid state to the gaseous state. With boiling there is thermal energy capable of increasing the motion of water molecules overcoming electrostatic force.

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Answer 2

Answer:

1) B. determining what data to collect

2) C. Heat samples of water and ethanol in two separate beakers using a Bunsen burner. Measure the temperatures at which the samples boil using a thermometer. Conduct several trials and record the average temperatures as the boiling points.

3) B. Heat energy overcomes the forces of attraction between the molecules of the substance, so the molecules can move more freely.

4). The addition of thermal energy causes the motion of water molecules to overcome electrostatic forces.

Explanation:

I think these are the answers, i'll confirm when I finish the test.