Mixtures

Mrs. Hutson's science students were dissolving sugar cubes in water to understand things that impact how fast (rate) sugar would completely dissolve in the water.

Which approach could be used to slow down how fast the sugar cubes completely dissolved?

• heat the water to its boiling point

• decrease the water's temperature

• grind the sugar into very small pieces

• stir the solution at a faster rate

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

NGSS.MS-PS3-5

A group of students collected a bucket of water from a neighboring pond to analyze.  The students noticed the bucket had dirt, sand, and wood particles at the bottom.  A ________ system would allow the students to quickly analyze the water by separating it from the particles in the bucket.

• magnetic

• floatation

• evaporation

• filtration

Ocean water contains dissolved salt (NaCl); however, it is possible to separate the salt from the water.

Which technique would be the BEST way to separate the salt from the water?

• Sift the salt out of the water with a kitchen strainer (i.e., a sieve).

• Filter the salt out of the water with filter paper.

• Use a magnet to attract the salt molecules.

• Apply heat to evaporate the water leaving the salt.

Tags

NGSS.MS-PS3-3

NGSS.MS-PS3-4

A scientist wants to change the concentration of two identical solutions.  She adds a solute to one of the solutions, _______ the concentration.  She adds solvent to the other solution,  _______ the concentration.

• decreasing, not changing

• increasing, decreasing

• not changing, increasing

• decreasing, increasing

The students place a teaspoon of sand in a 100ml beaker of water and stir briskly for one minute.  Next, the students add a teaspoon of salt (NaCl) to another 100ml beaker of water and stir briskly for one minute. What happens after 30 minutes?

• The majority of both salt and sand dissolved, but some salt or sand could be seen on the bottom of each beaker.

• The salt settled at the bottom of the beaker, but the sand was completely dissolved and could not be seen.

• The sand and salt both dissolved completely in the water and no particles of either could be observed.

• The salt dissolved and was no longer visible, but the sand had settled to the bottom of the beaker.

Tags

NGSS.MS-PS1-2

Why do some solutes dissolve faster in hot water?

• Cold water has more gravity, causing the molecules to move slower and solute to dissolve quicker.

• Hot water has more volume than cold water, which prevents the solute from being able to dissolve.

• Hot water has more energy, causing the molecules to move faster and the solute to dissolve quicker.

• Cold water has more oxygen than hot water, which prevents the solute from being able to dissolve.

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-5

physical combination of substances that can still be separated easily

• mixture

• solution

• solute

• solvent

the process that separates solids from liquids

• dilute

• filtration

• separate

• strainer or sieve

a special type of mixture that forms when one substance dissolves in another

• soluble

• solution

• insoluble

• dilute

Tags

NGSS.MS-PS1-2

to form a solution by mixing evenly

• filtration

• soluble

• dissolve

• insoluble