Elements, Compounds, Mixtures
Is salt an element, compound, or mixture?
compound (NaCl)
True/False: Acids taste bitter.
False. BASES taste bitter
Water has several properties that affect living and non-living things on Earth. Which is not a property of water that we have learned?
A) cohesion
B) lipid-solubility
C) surface tension
D) adhesion
B
physical change
2NaCl + Fe2
Sodium (2), Chlorine (2), Iron (2)
Ryan mixes olive oil and water in a jar, and watches as little globs of oil form around the top. He wonders if this is a homogeneous or heterogeneous mixture. What type of mixture is this?
Heterogeneous; it is not evenly distributed
True/False: All acids are harmful, and all bases are beneficial to the human body.
False; we need both!
adhesion
Which of the following is not evidence of a chemical change?
A) odor change
B) evaporation
C) color change
D) gas production
B. state of matter changes are physical
Balanced or unbalanced?
H2 + O2 ---> H2O
unbalanced
Draw an example of a compound on the board.
??
A) 4.3
B) 3.2
C) 7.1
D) 5.5
C. Alkaline means basic
What property of water allowed the toothpick to float on top of the water (from our water lab)?
cohesion; the water molecules stick together, forming a kind of net
Jeff is cooking marshmallows over a fire, and notices the marshmallow melting. Gregory notices that it is burning a little. Jeff says this is a physical change. Gregory says it is a chemical change. Who is right?
Is this equation balanced or unbalanced?
6H2O + 6CO2 ---> 6O2 + C6H12O6
balanced
Draw a heterogeneous mixture on the board.
??
List these from most acidic to most basic:
A. 4.2
B. 2.3
C. 8.0
D. 0.2
D, B, A, C
What property or properties of water allow for capillary action (the movement of water upwards against gravity) in plants?
cohesion and adhesion
Give two examples of a chemical changes that happen to you every day.
eating, breathing, cooking, using batteries, etc.
Label the elements and count the atoms of each element in this formula:
3Fe2 + 4H2O (B2K3)2
Iron = 6
Hydrogen = 8
Oxygen = 4
Boron = 16
Potassium = 24
Explain why unfiltered rain water is acidic.
burning of fossil fuels, normal carbon dioxide gas in the atmosphere
Ms. Martin is making bread. She makes the dough, and lets it rise for a few hours. She then cuts little slices in the top of the dough before she puts it in the oven. The oven cooks the bread until it forms a crispy crust on the bottom. Ms. Martin wants to know when the chemical change happened. When did the bread undergo a chemical change?
fermentation when the dough rose and when the bread was cooked in the oven
Connor is using combining baking soda and vinegar in the lab. He weighs both the vinegar and baking soda before combining, and notices that the weight of the solution is not the same as the weight before. Connor says that the reaction caused some of the vinegar to disappear. Is Connor correct? Explain.
Law of Conservation of Mass; the mass had to go somewhere. It likely went into the air as a gas was produced from the chemical reaction