Substances
Everything in the universe that has mass and takes up space is called ________________
Matter
Why can mixtures be separated by physical methods, but compounds cannot?
Because the substances in mixtures are not chemically combined.
Why does Italian salad dressing (vinegar and oil) need to be shaken before using?
Because it’s a suspension and the particles settle over time.
Convert 2.567 Km to Meters
2567 Meters
Write 5,000 in scientific notation.
5 x 103
Which is always true about elements but NOT about compounds:
A) Made of only one type of atom
B) Chemically combined in fixed ratios
C) Can be broken down into simpler parts
Which type of mixture would make it easiest to see the different parts — homogeneous or heterogeneous?
Heterogeneous, because the substances are not evenly mixed and the particles are visible.
Which type of mixture has particles too small to settle but large enough to scatter light?
A colloid
A container holds 2.5 liters of water. How many centiliters is that?
250 centiliters
Write 0.0042 in scientific notation.
4.2 x 10-3
If you break down water into hydrogen and oxygen, why is it no longer a compound?
Because compounds are chemically combined in fixed ratios, and breaking it down separates it into its individual elements.
Give an example of a separation method that uses differences in boiling points to separate substances.
Distillation
Colloids can’t usually be filtered out. Name one method scientists use to separate colloids and explain why it works.
A centrifuge — it spins mixtures at high speeds, forcing particles to separate by size/density.
A pencil is 0.085 meters long. Express this length in centimeters.
8.5 cm
Write 67,800,000 in scientific notation.
6.78 x 107
Explain why a molecule of oxygen gas (O₂) is NOT a compound, but a molecule of carbon dioxide (CO₂) is.
O₂ has only one type of atom (oxygen), so it’s still an element; CO₂ has two different atoms (carbon and oxygen), so it’s a compound.
You have a clear mixture of salt and water. Which test would help you decide if it’s a solution (homogeneous) or a colloid?
Shine a light through it to check for the Tyndall Effect (colloid scatters light, solution doesn’t).
List the 3 components of blood along with their percentages.
Plasma - 55%
RBS - 45%
WBC- 1%
A race is 5 kilometers long. How many centimeters is the race?
500,000 cm
Write 0.000000000321 in scientific notation.
3.21 x 10-10
Name 5 elements.
Oxygen, Hydrogen, Carbon, Nitrogen, Chlorine, Sodium...
Imagine you are given a mixture of sand, salt, and water. Describe the steps you would use to separate all three.
Use filtration to remove sand, then evaporate or distill the water to separate it from salt.
Why does muddy water eventually clear up if left undisturbed, while milk does not?
Muddy water is a suspension, so its particles are large enough to settle out over time. Milk is a colloid, so its particles are small enough to stay evenly dispersed and won’t settle.
A medicine bottle contains 0.004 kilograms of medicine. How many milligrams is that?
0.004 kg = 4 g
4 g = 4,000 mg
Convert 5.127 x 10-5 to standard notation.
0.00005127