Question

model 3 – boiling points of alcohols

alcohol name | formula | number of carbons | volume of alcohol (ml) | boiling point (°c) | room pressure (kpa)
--- | --- | --- | --- | --- | ---
methanol | ch₃oh | 1 | 75 | 64.7 | 101
ethanol | ch₃ch₂oh | 2 | 75 | 78.4 | 101
propanol | ch₃ch₂ch₂oh | 3 | 75 | 97.1 | 101
butanol | ch₃ch₂ch₂ch₂oh | 4 | 75 | 117.7 | 101
pentanol | ch₃ch₂ch₂ch₂ch₂oh | 5 | 75 | 137.9 | 101

1. describe the similarities and differences in the five alcohols used in the model 3 experiment.

1. consider the experiment that produced the data in model 3.

a. what variable was purposefully changed in the experiment?
b. what variable changed as a result of changing the variable listed in part a?

1. what variable(s) in the model 3 data table remained constant among all the trials?

Explanation:

Question 8

Similarities: All are alcohols (contain -OH group), have the same volume (75 mL) and room pressure (101 kPa). Differences: Different number of carbon atoms (1 - 5), different boiling points (64.7 - 137.9 °C), different molecular formulas (varying carbon chain lengths).

The purposefully changed variable (independent variable) is the number of carbon atoms in the alcohol (or the type of alcohol, as each has a different carbon count). Looking at the table, the "Number of Carbons" column changes (1, 2, 3, 4, 5) while others like volume and pressure are constant.

The variable that changes as a result (dependent variable) is the boiling point. As the number of carbons (independent variable) changes, the boiling point (from 64.7 °C to 137.9 °C) changes.

Answer:

Similarities: All are alcohols (contain hydroxyl group), same volume (75 mL) and room pressure (101 kPa). Differences: Different carbon atom counts (1–5), boiling points (64.7–137.9 °C), molecular formulas (varying carbon chains).

Question 9a