Density Quiz Let’s review

Inquiry Science 1 – Density Quiz Directions: Read all questions carefully. You must show your work to get credit. All calculations must be labeled with proper units. You have gathered the following data in the lab. Use the data to calculate the density of each of the Liquids.   Trial 1 Trial 2 Trial 3 Samples Mass g Vol.mL Density Vol. mL Liquid 1 4.45 5 9.05 10 22.92 25 Liquid 2 3.95 8 20.16 Liquid 3 6.06 12.42 31.37 g/mL g/mL g/mL 0.89 0.91 0.91 0.79 0.80 0.81 1.21 1.24 1.25 Sketch what you would see in the graduated cylinder. Make sure to clearly label each substance.

Draw a best-fit line for each Liquid. Make sure to label each line. 2. On a separate piece of graph paper, graph the mass and volume data for each liquid. Draw a best-fit line for each Liquid. Make sure to label each line. Volume (mL) Mass (g) 34 32 30 28 26 24 22 20 18 16 14 12 10 8 6 4 2 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Liquid 1 Liquid 2 Liquid 3

What does the slope of the best-fit line represent? Liquids 1, 2 and 3 are insoluble in each other. You put these liquids into a graduated cylinder. Draw a sketch of what you would expect to see. Density Liquid 2 Liquid 1 Liquid 3 6. You take a piece of chalk into the lab and make the following measurements: Mass = 2.49 g Volume of water in graduated cylinder = 20mL Volume of water + chalk = 22.5 mL What is the density of the chalk? D=m/V 22.5mL -20.mL 2.5mL 2.49g 2.5mL 0.996mL or 1.0mL

What would you expect the density of the bigger piece of chalk to be? You drop the chalk into the graduated cylinder from Question 5. Where would you expect the chalk to settle? If you got another piece of the same type of chalk, and the new mass was 5.62g, what would you expect its volume to be? What would you expect the density of the bigger piece of chalk to be? Between liquid one and three. Liquid one has a density of 0.91 g/mL. Liquid 3 has a density of 1.25 g/mL. Density of the chalk was 1 or 0.996 g/mL and is in between the two values D= m/V D *V= m D V=m/D 0.996g/ml= (5.62g)/v (5.62g)/(0.996g/mL)=5.64mL OR 5.62g/1g/ml= 5.62g/mL the same. The density will not change with the different sizes of chalk

10. You put three liquids into a graduated cylinder, Liquid A, Liquid B, and Liquid C. Liquids A and C are soluble in each other. Liquid B is not soluble in either A or C Liquid A and C are soluble which means they will mix together. They also have a more moderate slope and are less dense. They will be on top A and C B Liquid B is not soluble in either A or C and will not mix. It also has a steeper slope so it will sink to the bottom

This graph plots the mass/volume of lead, zinc, and aluminum This graph plots the mass/volume of lead, zinc, and aluminum. What is the density for each solid? Zinc= 23g/3.25mL= 7.08g/mL Lead= 12g/1mL= 12g/mL Aluminum= 4g/2mL= 2g/mL

Quick Definition Atoms: Molecule: Smallest unit of an element, which still has the same properties of an element http://en.wikipedia.org/wiki/File:Atom_diagram.png Molecule is a group of atoms that have a neutral charge http://www.faculty.colostate-pueblo.edu/linda.wilkes/111/2a.4.gif http://images.tutorvista.com/content/atoms-molecules/homo-hetero-atomic-molecule-formation.jpeg

Stop and Think pg 84 1-4 1. The gas produced was CO2 the same gas we exhale during breathing. Suppose both the cap and the balloon methods captured exactly 50 particles (molecules) of CO2 A) sketch these gas particles for both methods (balloon and cap) include highlight comments and captions for each sketch. water What I see: Gas particles are farther apart in the balloon method What it means: Gas density is greater in the capped method; increasing the bottles pressure Modified by” Tiffany adamdshttp://www.allproducts.com/plastic/youcheng/plastic_soda_bottles-l.jpg http://2.imimg.com/data2/PX/HN/MY-224366/double-lip-closures-250x250.jpg

Stop and Think pg 84 1b) Why should there be the same number of gas particles in each bottle, provided the same amount of water and the size tablet? Matter can neither be created nor destroyed (Law of Conservation), so the amount of gas should have been the same no matter how you conducted the experiment. As long as the same amounts of water and tablet were used.

Stop and Think pg 84 1-4 1c) Are the carbon dioxide molecules moving or stationary? How do you know? The molecules have to be moving because otherwise the balloon/bottle would collapse. There has to be something in the balloon after the reaction because it began to inflate Something extinguished the flame and we could see it wasn’t a solid or a liquid We can physically see that there were no solids or liquids in the balloon The only way pressure could have built up in the balloon/bottle would be for those molecules to collide with each other and move around the container

Stop and Think pg 84 1-4 1d) What does that look like? Air molecules Collision with balloon

Stop and Think pg 84 1-4 2. In which method is the pressure inside the bottle the greatest? Give evidence. The capped bottle has more pressure inside. Since the capped bottle was started at room pressure and remained the same size (volume), the carbon dioxide gas had to produce extra pressure above room pressure All the gas that was created had to go somewhere. In the balloon, there was more volume so less pressure in that bottle In the capped bottle? Can’t go anywhere so there is a higher pressure

Stop and Think pg 84 1-4 3. In which method is the density of the carbon dioxide gas the greatest? What evidence supports your answer? The capped bottle has the higher gas density. You know this because the same amount of molecules are produced for both methods (provided the tablet was the same size), so mass was the same. The volume was less because the bottle was capped and therefore there was not the extra room for the molecules to go as in the balloon. Since the volume was less (mass the same), then the density is greater. water

Stop and Think pg 84 1-4 4. Sketch a graph to show the relationship between density and pressure for a gas like carbon dioxide at a constant temperature. Include highlight comments and a caption. What will happen to the bottles if the volume decreased? Would the density increase or decrease? If the density increases what then would happen to the pressure? Would it increase or decrease? What I See: Line with a constant positive slope What it Means: Gas density is proportional to pressure Gas density This graph shows how density of a gas increases as pressure increases. This is due to molecules begin pushed together. With more molecules in the same place the density increases Pressure

Stop and Think Part II Pg 87 1-4

Stop and Think pg 87 1) Which half of the reaction, reactant or product, had a greater mass when you constructed only one molecule each of methane, oxygen, carbon dioxide, and water? Explain why using the correct symbols for each atom and the law of conservation of matter. Reactant Product CH4 + O2 CO2 +H2O The reactant side had more mass (before balanced). That is because 1 methane molecule (CH4) and one oxygen molecule (O2) have a total of 7 atoms, each one about the same mass. Remember, that atoms of different elements have different mass. Most model kits do not model differences in atomic mass. This product side has a total of 6 atoms due to 1 carbon dioxide (CO2), and 1 water molecule (H2O)

Stop and Think pg 87 2) Which molecules did you have to build more of in order to show conservation of matter? Explain how you selected which molecules and how many. One more molecule of oxygen (O2) and that created one more molecule of water in the product (H2O). Once that oxygen molecule was built it produced a second water and the equation was able to obey the law of conservation. All the atoms on the reactant side = all the atoms on the product side

Stop and Think pg 87 3) Explain why the mass of the candle changed after 2 minutes of combustion, considering the law of conservation of matter. The candle lost mass because carbon dioxide was formed (gas) and floated away. We saw from the previous experiment (antacid) that carbon dioxide did indeed have mass (balloon). So when the candle lost carbon [(C4OH4)2] in the form of carbon dioxide it lost mass.

Stop and Think pg 87 4) What steps did you take in the antacid tablet in water reaction that were different from the burning candle reaction in regard to the conservation of matter? Explain why those didn’t work. In the soda bottle reaction we captured all the gas produced from the reaction. In the candle, gas was lost to in the air and dispersed throughout the room. The candle burning was not a closed system