Properties of Water and Enzymes

Statement: When an ionic compound such as sodium chloride (table salt) is placed in water, as shown in the figure above, water molecules surround and separate the positive and negative charge.
Question: What happens to the Sodium ions and Chloride ions in the solution?

• Both Sodium and Chloride ions dissolve in water  
• Both Sodium and Chloride ions are destroyed  
• Both Sodium and Chloride ions hide temporarily   Option 3 (optional)
•   The Sodium ions are destroyed, the Chloride ions hide temporarily  

Tags

NGSS.MS-PS1-2

In Zoe's science experiment, water is the ________________________ while Sodium Chloride (Table Salt) is the __________________________.

• solvent, solute

• solute, solvent  

• solute, solute  

• element, molecule  

Tags

NGSS.MS-PS1-2

Question: Emma and David are comparing the acidity of different substances. Order these items in order of increasing acidity:Coffee, Seawater, Ammonia, Lemon Juice, Blood

• Lemon Juice, Seawater, Ammonia, Blood, Coffee

• Ammonia, Seawater, Blood, Coffee, Lemon Juice

• Blood, Coffee, Lemon Juice, Ammonia, Seawater

• Lemon Juice, Coffee, Blood, Seawater, Ammonia

Question:  Arjun and Isla are discussing water molecules. What does it mean when a molecule is said to be “polar”?

• The molecule has tendency to absorb a lot of heat, therefore it remains 'cold' easily

• The molecule has an even distribution of charges, all parts are positive

• The molecule has an even distribution of charges, all parts are negative

• The molecule has an uneven distribution of charges, some parts are positive while others are negative

Tags

NGSS.HS-ESS2-5

Statement: Water may be one of the most familiar substances on the planet, but it certainly isn’t ordinary. In fact, water’s unique chemical properties make it so complicated that even after decades of research, scientists still have much to learn about this remarkable and versatile substance.That’s water, as in the clear, sparkling fluid that covers three quarters of the Earth’s surface—not to mention the basis of life as we know it, and possessor of the world’s most recognizable chemical formula (H₂O). Water is everywhere. And yet, scientists are still learning about its properties.Water simply doesn’t behave like other liquids. During a science class, Zoe and Aria were discussing the unique properties of water. Question: Which of the following is not a special property of water?

• Water has the ability to moderate temperature

• Water is polar, therefore it is very adhesive

• Water contracts when it freezes

• Water is polar, therefore it is very cohesive

In a classroom experiment, Mason and Charlotte are studying water molecules. According to their observations, a hydrogen bond can form between a hydrogen atom of one water molecule and which atom of another water molecule?

• Carbon

• Hydrogen

• Oxygen

• Sodium

Michael and Aria were conducting an experiment in their science class. They observed that when they tried to mix oil and water, the two liquids did not combine. Reading Passage: Water's polarity allows it to dissolve other polar substances very easily. When a polar substance is put in water, the positive ends of its molecules are attracted to the negative ends of the water molecules, and vice versa. The attractions cause the molecules of the new substance to be mixed uniformly with the water molecules. Water dissolves more substances than any other liquid - even the strongest acid! Because of this, it is often called the 'universal solvent.' The dissolving power of water is very important for life on Earth. Wherever water goes, it carries dissolved chemicals, minerals, and nutrients that are used to support living things.  Substances that are not polar like water, for example oil, do not mix into water.  
Question: Which property is responsible for the fact that water and oil do not mix?

• density

• mass

• phase

• polarity

Grace and Avery are conducting an experiment in their chemistry class. They are studying the properties of acids and bases. Grace adds an acid to a beaker of water and observes the changes. Reading Passage: In water (H₂O), a small number of the molecules dissociate (split up). Some of the water molecules lose a hydrogen and become hydroxide ions (OH⁻). The "lost" hydrogen ions join up with water molecules to form hydronium ions (H⁺). In pure water, there are an equal number of hydrogen ions and hydroxide ions. The solution is neither acidic or basic.An acid is a substance that donates hydrogen ions. Because of this, when an acid is dissolved in water, the balance between hydrogen ions and hydroxide ions is shifted. Now there are more hydrogen ions than hydroxide ions in the solution. This kind of solution is acidic.A base is a substance that accepts hydrogen ions. When a base is dissolved in water, the balance between hydrogen ions and hydroxide ions shifts the opposite way. Because the base "soaks up" hydrogen ions, the result is a solution with more hydroxide ions than hydrogen ions. This kind of solution is alkaline.Question: When added to water, how does an acid affect the pH and H⁺ concentration?

• Both pH and H⁺ decrease.

• Both pH and H⁺ increase.

• The pH decreases while the H+ increases.The pH decreases while the H⁺ increases.

• The pH increases while the H⁺ decreases.

During a science class, Ava and Zoe were discussing the properties of water. Ava mentioned that water typically has a pH of 7 and therefore is considered neutral. What ions are present in neutral water?

• hydrogen and hydronium ions.

• hydroxide and hydronium ions.

• hydrogen and hydroxide ions.

• oxygen and hydrogen ions.

James is conducting an experiment in his chemistry class. According to the figure above, a solution with a pH of 11 is

• acidic

• alkaline

• neutral

• a buffer