chemistry density lab question 1. if there was any variation from the accepted value, why do you think it could have occurred? 2. Supposed the outside of the glassware is not completely dry when it is weighed with the water in it, but it is dry when weighed at other times. Explain how that error will affect your density ( for instance, will the density be higher or lower that it should be?). 3. Suppose we have equal volumes of aluminum and a mystery metal. the mystery metal has a mass of 80g. what is the density of the mystery metal if the aluminum has a mass of 19g and a density of 2.64g/ml?

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Name Advance Study Assignment: Densities of Solids and Liquids The advance study assignr nents in his laboratory manual re red in the experimcnt you will required in the some detail how that data can be used to obeain often include the guiding principles as well the steps in each calculation by yourself, you should have necessary calculations on the basis of the data you obtain is the labonesy giedt.meyni' main. the desired resalts. la the adrance stuly as the specific 1. Finding the volume of a flask. A student obtained a clean, dry glass-ssoppered flask. She weighed the flask and stopper on a walytic balance and found the total muss to be 33.695 g. She then filled the flask with water and okeained aa the full stoppered flask of 64356 g. From these data, and de fact tut the lempenturedtcldunn the density of water was 09978 g'cm2, find the volume of the stoppered flask a. First we need to obain the mass of the water in the flask. This is found try recogriÃ¡ng that the mas of a sample is equal to the sum of the masses of its parts. For the illed stoppered flank Mass of filled stoppered naskemass of eå¥stoppered nak + mndwaer. so mass of water mass of filled flask- mass of empty flask Mass of water Many Many mass and volume measurements in chemistry are made by the method used in la. This method is called measuring by difference, and is a very useful one b. The density of a pure substance is equal to its mass divided by is volume m volume mass density mass or Density -volume or volume densiy The volume of the flask is equal to the volume of the water it contains. Since we know the mass and density of the water, we can find its volume and that of the flask. Make the necessary calculation cm Volume of water e volume of Task - Finding the density of an unknown liquid. Having obtained the volume of the flask, the student emptied the flask, dried it, and filled it with an unknown whose density she wished to determine. The mass of the stoppered flask when completely filled with liquid was 58 540 g. Find the density of the liquid. 2. g a. First we need to find the mass of the liquid by measuring by difference g= g Mass of liquid= (continued on following page)

1.A block of metal has dimensions 5.00 cm x 2.50 cm x 3.00 cm. Calculate the volume of the block, showing the answer to the correct number of significant figures and unit.

2.If the block of metal from question 2 has a mass of 405.3 g, what is the density of the metal? Calculate the density, showing the answer to the correct number of significant figures and correct unit.

3.Convert the numerical value of the density in question 2 from units of grams per cubic centimeter (g / cm3) to milligrams per milliliter (mg / mL). Note:

-there are 1000 milligrams in a gram.

-the volume unit cubic centimeter cm3 equals the milliliter mL.

Keep the new density to the same significant figures as you reported in question 2

4.A finely-powdered white solid is known to be homogeneous mixture rather than a pure substance. A sample of this solid completely dissolves in water. Give TWO possible substances that could make up this solid mixture, and briefly explain your choices.

5.If your percent SALT in Lab 2 is relatively low, it can be assumed that some salt did not go into the filtrate (the liquid that passes through the filter paper), but rather may have been trapped with the sand. Explain briefly how you could recover any of this "missing" salt?

6.A brand of aspirin claims to contain 325 mg (1 g = 1000 mg) of aspirin per tablet. In addition to pure aspirin, a tablet also contains a non-active filler. We assume that the tablet contains only these two components: aspirin and filler. If a single tablet weighs 1.17 g, calculate the percent filler. Hint: calculate percent aspirin FIRST using the formula

% aspirin = [ (mass aspirin Ã· mass tablet) x 100], the find % filler. When using this formula, make sure the masses of aspirin and tablet have the same units.

7.Water has a density of 1.00 g/mL, and chloroform has a density of 1.49 g/mL. These two liquids do not mix with each other, but rather, form two layers when combined.

8.Equal volumes of water and chloroform are placed in a beaker. A piece of nylon is dropped in the beaker, and is seen to float the the interface (the boundary) of the two liquid layers.

Give a possible value for the density of nylon, including the correct units. Explain your answer briefly.

9.A procedure similar to that used in Lab 3 was performed to find the density of cyclohexane, which has an actual density of 0.779 g/mL, Due to poor lab technique, an experimental density of only 0.663 g/mL is found. Calculate the percent error for the density. Give your answer to the correct number of significant figures.

10.Two white powders are given to you. One is pure sodium bicarbonate, and the other is baking powder (a mixture of sodium bicarbonate and a weak acid like citric acid). Which single test (NOT counting the visual examination with a hand lens) used in Lab 3 allows you to distinguish sodium bicarbonate from baking powder? Explain your answers completely.

11.Gold has a specific heat of 0.129 J/g^oC. If a piece of gold (initially at 10.0^oC) is dropped into hot water, the final temperature of both the gold and the water is measured as 70.9^oC. If it is known that 4560 J of heat transferred from the hot water to the gold, what is the mass of the piece of gold in grams? Give your answer to the correct number of significant figures.

12.It is stated in the Introduction to Lab 4 that q_water = -q_metal. This equation means that if a hot piece of metal is placed in water, the amount of heat given off by the metal is exactly equal to the amount of heat absorbed by the water. However, this equation is not always accurate, because not all of the heat from the metal necessarily goes to the water. Where else can some of the heat go if it is not absorbed by the water?

13.A certain brand of breakfast cereal claims to have 100 Calories per 28 gram serving. 150.0 grams of cereal are burned using a procedure similar to that used in Lab 4. How many calories of heat are released? Note 1 food Calorie (capital C) = 1000 heat calories (lower case c)

14.The oxalate anion C2O42- is found in many dark green vegetables, including spinach, swiss chard, and collard greens. When cations react with oxalate, the resulting ionic compounds are insoluble in water except Group I A oxalates (e.g. compounds of lithium, sodium, potassium, etc. and oxalate) and ammonium oxalate (NH4)2C2O4. These exceptions are soluble in water.

15.Spinach leaves are cut into small pieces, mashed with small amounts of boiling water, and filtered through filter paper to remove the insoluble spinach material. The resulting aqueous extract contains the oxalate anion.if a small amount of the spinach extract is mixed with a small amount of a calcium acetate solution, Ca(C2H3O2)2(aq), what do you expect will be observed?

16.If a small amount of the spinach extract from question 16 is mixed with a small amount of a potassium acetate solution, KC₂H₃O₂(aq), what do you expect will be observed?

17.If a hot water extract of another vegetable is mixed with calcium acetate solution and a white precipitate is observed, does this automatically indicate the presence of the oxalate anion in this vegetable? Explain your answer.