Question

You observe two beakers containing clear liquid and ice cubes. In the first beaker, the ice cubes are floating. In the second, the ice cubes are on the bottom of the beaker. Write a hypothesis to explain the difference in your observations about the two beakers.

Short answer

The liquid in beaker 1 is less dense than ice; in beaker 2, it is denser.

Step-by-step solution

Identify Known Variables

First, let's identify what we know from the problem. We have two beakers: one where ice cubes float and another where ice cubes sink to the bottom. We know ice is less dense than water, which is why it typically floats.

Define Hypothesis for Beaker 1

Since ice cubes are floating in the first beaker, we can hypothesize that the liquid in this beaker is water or another liquid where the density is less than or equal to the density of ice.

Define Hypothesis for Beaker 2

In the second beaker, the ice cubes are sinking, which suggests that the liquid in this beaker is denser than ice. This implies that the liquid might be something denser than water, like a saltwater solution or another liquid known for its greater density than water.

Formulate Overall Hypothesis

Considering both observations, form the hypothesis: the first beaker contains a liquid with a density equal to or less than that of ice, allowing the ice to float, whereas in the second beaker, the liquid is denser than ice, causing the ice cubes to sink.

Key concepts

Hypothesis Testing

Hypothesis testing is a method used to make decisions or inferences about the properties of a population based on sample data. It is a fundamental aspect of conducting scientific experiments and making predictions.

• First, an idea or assumption, known as a hypothesis, is formulated based on initial observations.
• This hypothesis is then tested by conducting experiments and making further observations to see if the results support or refute the initial idea.
• The core idea is to gather evidence and decide if there is enough data to accept or reject the hypothesis.

In the context of the given exercise, hypothesis testing helps explain why ice behaves differently in two beakers. By observing whether the ice floats or sinks, we can form and test hypotheses about the liquid's density.

Floating and Sinking

Floating and sinking are concepts that relate to the density of objects and their surrounding mediums. An object floats if it is less dense than the fluid it is placed in, and it sinks if it is denser than the fluid.

• Density is a measure of how much mass an object has in a given volume, often expressed in kilograms per cubic meter (kg/m³) or grams per cubic centimeter (g/cm³).
• Understanding floating and sinking involves comparing the density of the object to the density of the liquid.
• This can be demonstrated with the example of ice cubes:
  • Ice, in its solid form, is less dense than liquid water, which is why it typically floats on water.
  • If ice sinks, it indicates that the liquid it is in is denser than the ice itself.

In the given exercise, observing the different behaviors of ice cubes in two beakers gives us clues about the relative densities of the liquids compared to ice.

Density of Liquids vs Ice

The density of liquids versus ice is an interesting area of study, especially when considering how different liquids interact with ice. Ice is generally less dense than water but can have varying interactions with other liquids.

• Water has a unique density of about 1 g/cm³ at 4°C, making ice, at about 0.92 g/cm³, less dense than water.
• Other liquids can range widely in density:
  • Oil is usually less dense than water, which would also allow ice to float.
  • Saltwater, on the other hand, is more dense due to the dissolved salts, potentially causing ice to sink, as seen in Beaker 2 of the exercise.
• Understanding which liquids are denser than ice can predict whether ice will float or sink in them. If ice is in a liquid denser than 0.92 g/cm³, it will sink, as its density is lower.

Examining different liquid densities helps form hypotheses about what might be inside each beaker in the exercise.