OpenSciEd Unit 3 Assessment

Use evidence from patterns in the periodic table and information presented in this assessment as support for your explanation.

• The periodic table shows recurring chemical properties.

• The periodic table is organized by atomic number.

• The periodic table includes metals, nonmetals, and metalloids.

• The periodic table was first created by Dmitri Mendeleev.

Which mineral, potassium carbonate or magnesium bicarbonate, would most likely form soap scum by combining with stearate ion(s) to form an insoluble compound?

• Potassium carbonate

• Magnesium bicarbonate

What is a long-term consequence of using hard water in household cleaning?

• Decreased time spent on cleaning

• Increased wear and tear on fabrics and surfaces

• Improved cleanliness and hygiene

• Reduced costs on cleaning supplies

What is a practical tip for reducing soap scum in a household with hard water?

• Increase the use of bleach

• Use purified bottled water for cleaning

• Install water-softening equipment

• Only use hot water for cleaning

Which of the following is a solution to prevent soap scum buildup in showers and sinks?

• Regular cleaning with vinegar

• Using more soap

• Increasing the water temperature

• Using only cold water

How is it possible that the oxygen atom in the water molecule is able to pull the sodium ion away from the oxygen molecule in the stearate ion? Construct an explanation of this phenomenon using differences in electronegativity between the atoms in water molecules and stearate ions. You may wish to use the following table to help you think through your evidence.

• The oxygen atom in water has a higher electronegativity than the oxygen in the stearate ion, allowing it to attract the sodium ion.

• The sodium ion is more attracted to the hydrogen atoms in water than to the oxygen in the stearate ion.

• The oxygen atom in the stearate ion has a higher electronegativity than the oxygen in water, allowing it to attract the sodium ion.

• The sodium ion is equally attracted to both the oxygen in water and the oxygen in the stearate ion.

Why does hard water lead to increased use of cleaning products?

• Because it contains more cleaning agents

• Because it is more effective at cleaning

• Because it reacts with cleaning products to reduce their effectiveness

• Because it is less polluted

How do the particle-level structures help further explain what causes soap scum?

• By showing the interaction between soap molecules and minerals in water

• By illustrating the chemical reaction between soap and air

• By demonstrating the effect of temperature on soap

• By explaining the role of soap in cleaning surfaces

Develop an initial model to explain what you think might be happening to cause soap scum to form on the sink drain. Be sure to include the following components of the system and their interactions in your model: - drain surface - water molecules, including partial charges

• Soap scum forms due to the interaction between the drain surface and water molecules with partial charges.

• Soap scum is caused by the absence of water molecules near the drain surface.

• Soap scum formation is unrelated to the drain surface and water molecules.

• Soap scum forms only when there is no interaction between the drain surface and water molecules.

Which of the following is a common visible effect of soap scum buildup?

• Increased transparency of water

• Formation of bubbles in water

• A greasy film on bathroom fixtures

• Water turning into a light blue color