Scientific Method/
Density
Density
The quantity to be changed in an experiment is called the
independent variable
Why do liquids have a definite volume but no definite shape?
Their particles are loosely bound but can slide past each other.
Define matter
Anything that has mass and takes up space
Which is not a chemical change? (Select all that apply)
A. Dissolving
B. Decomposing
C. Boiling
D. Corroding
A. Dissolving
C. Boiling
Where are all the places on the heating and cooling curve that a gas will be found?
D and E
If the density of substance A is greater than the density of substance B, will substance A float on substance B?
No - the substance with the lower density will float
What type of property is density?
Physical property that doesn't change with amount (intrinsic)
Why is salt not an element?
Because salt is made of sodium and chloride, making it a compound
Chemical changes differ from physical changes because in chemical changes:
A. new substances are formed
B. properties change
C. a change in mass occurrs
D. less energy change takes place
A. new substances are formed
C
How do you measure the volume of an irregularly shaped piece of metal?
Water displacement in a graduated cylinder
Are boiling point and freezing point chemical or physical properties? Why?
Physical - boiling or freezing a substance does not change it's chemical composition (does not change it to a new substance)
Which of the following is true about compounds:
They have properties different from those of their component elements
Define accuracy
How close data (or the average of the data) is to the accepted or correct value
What is moving from a solid to a gas called?
Sublimation
A beaker has a mass of 34 grams. When the beaker is filled with 58 mL of a fluid it has a mass of 75 grams. What is the density of the fluid?
0.71 g/mL
Which of the following is a chemical property of magnesium?
A. Oxidizes to a white powder
B. Melts at 650 degrees C
C. Has a density of 1.74 g/mL
A. Oxidizes to a white powder
Why are the following not heterogeneous mixtures: salt, baking soda, air?
Salt and baking soda are compounds, air is a homogeneous mixture
Two solutions are added together and produce a cloudy substance. What is the evidence that a chemical change has occurred?
Precipitate
What is the normal melting point of the substance shown in the phase diagram?
200 degrees C
Usually when a solid is heated, its volume increases. How does this increased temperature affect the density of the substance?
It decreases
In trying to identify a liquid compound, a student find that it has the same density, freezing point, and boiling point of a compound Z. Can the student reasonably assume that the liquid is in fact compound Z?
Yes - density, freezing point, and boiling point are often used to identify substances (they are intrinsic/intensive physical properties)
A sample of a pure white substance is heated and produces a reddish brown gas and leaves a brown residue in the test tube. The substance is most likely:
A. a solution
B. a compound
C. either an element or a compound
B. a compound
What are the evidences of a chemical change that we remember with the mnemonic "Please Excuse Coughs Sneezes and Burps"?
Precipitate, Energy change, Color change, change in Smell, Bubbles
Which of the following is not a physical property of water:
Freezing point of 0 Celsius
Made of hydrogen and oxygen
Sugar dissolves in it
Made of hydrogen and oxygen (that is a chemical property)