Density & Water Displacement
A metal sample has a mass of 78.5 g and a volume of 10.0 mL.
What is its density?
7.85 g/mL
A student investigates whether the temperature of water affects how quickly sugar dissolves.
What is the independent variable?
Water temperature
Calculate the number of moles in 134.2 g of water if 1 mole water = 18.02 g.
7.44 mol
Write the following numbers in scientific notation:
1) 45,100
2) 0.00000742
1) 4.51 x 104
2) 7.42 x 10-6
5x+12=2x+33
Express your answer in 3 sig figs.
x = 7.00
A liquid has a density of 1.26 g/mL. A graduated cylinder contains 18.25 mL of the liquid.
How many grams of liquid are present?
22.99 g
A student investigates whether the concentration of saltwater affects the electrical conductivity of the solution.
What is the dependent variable?
Electrical conductivity
Convert 2.75 days into seconds. Express your answer in scientific notation.
2.376 x 105 sec
Write the following numbers in standard notation:
1) 6.03 x 10-5
2) 8.45 x 108
1) 0.0000603
2) 845,000,000
3(x−5)=2x+9
Express your answer in 3 sig figs
x = 24.0
A substance has a density of 2.70 g/mL and a mass of 54.0 g.
What is its volume?
20 mL
A student changes the temperature of water to investigate its effect on dissolving time.
Name two components that should be kept constant.
Amount of sugar
Volume of water
Type/brand of sugar
Stirring rate
Container size
A car travels at 72.0 km/h. Convert its speed to m/s. Express your answer with 4 sig figs.
20.00 m/s
How many years has Ms. Y been teaching at WTHS? Only the team with the closest answer gets points!
12
4(2x−3)−5=3x+17
Express your answer in 1 sig fig
x = 7
A rock has a mass of 42.8 g. When placed into a graduated cylinder, the water level changes from 18.5 mL to 34.2 mL.
What is the density of the rock?
2.72 g/mL
A student wants to determine which of three antacid brands neutralizes acid most effectively.
What should the student change between groups? What should remain the same?
Change: Brand of antacid
Same: The amount/concentration of acid, amount of antacid, temperature, reaction time
A piece of metal has a volume of 4.25 cm³ and a density of 8.96 g/cm³.
What is its mass in milligrams? Express your answer in scientific notation.
3.81 x 104 mg
When is Ms. Y's birthday?
ONLY THE CLOSEST DATE GETS THE POINTS :)
March 19
(x+2)/3 + (2x−1)/4 = 10
Express your answer in 4 sig figs.
x = 10.73
A piece of an unknown metal has a density of 7.85 g/cm³ and a mass of 117.75 g.
If it is placed into a graduated cylinder containing 50.00 mL of water, what will the final water level be?
65 mL
A student wants to determine whether temperature affects the rate of a chemical reaction. They perform the following:
Trial Temp Mass of Reactant Reaction Time
1 20o 2.0 g 45 sec
2 30o 2.0 g 38 sec
3 40o 1.5 g 29 sec
4 50o 2.0 g 21 sec
The student concludes: “Higher temperature causes the reaction to occur faster.”
Explain why conclusion is valid or invalid.
Invalid because they tested 2 variables at once - changed temperature and mass of reactant.
A substance has a density of 7.85 g/cm³. Express this density in kg/m³.
7,850 kg/m3
7.85 g = 0.00785 kg
1 m3 = 1,000,000 cm3
(0.00785 x 1,000,000) = 7,850The mass of a single carbon atom is approximately:
1.99×10−23 g
Approximately how many carbon atoms would have a total mass of 2.99 g?
1.5 x 1023 atoms
A cylindrical metal sample with a mass of 0.13 kg has a radius of 20 mm and a height of 0.05 m. What is the density (in g/mL)? Express your answer with 4 sig figs.
V=πr2h
d = 2.070 g/mL