Lab_1_The Tools and History of Chemistry - Chemistry

This lab will make use of your ability to make Scientific Models, to use the Scientific Method, and to use the tools of Chemistry to do this.

Step 8

Mass a 10 mL graduated cylinder.

Record.

(Make sure your measurement is taken to the proper guesstimate)

Step 8

Fill the 10 mL graduated cylinder with exactly 10 mL of pure water.

Use a plastic pipette to get the volume exactly.

Mass the graduated cylinder and water.

Record.

(Make sure your measurement is taken to the proper guesstimate)

Step 8

Figure out the density of the pure water in the graduated cylinder.

Remember, density is the number of grams in one mL of liquid.

So…

Figure out the mass of the water (in grams).

Divide this figure by the volume (in mL) that you had (which was 10 mL of water).

Hopefully, your measurements were precise but were they accurate?

Pure water should have a density of 1 g / mL.

If your density isn’t 1 g / mL that’s OK.

Continued on next slide -

Step 8

In labs, you don’t make up data – use the numbers that you get, especially if you made the measurements to the proper significant digits (to the proper guesstimates).

You will now use the Scientific Method to figure out how many grams of salt dissolved into 10 mL of water is required to raise the density of the liquid up 0.1 g / mL.

One possible way of doing this is outlined in the next slides.

Step 8

Fill the 10 mL graduated cylinder with exactly 9 mL of pure water (this will allow room for the salt that will be added).

Use a plastic pipette to get the volume exactly.

Step 8

Fill a 10 mL graduated cylinder with exactly 10 mL pure water. Use a plastic pipette to get it exactly.

Step 8

mass of this minus mass of this

gives the mass of the vinegar used (record)

1) What organelle is shown at “A”? Picture of answers from “Word to Photoshop” originally in Verdana 16 font

Answer for this question

1) mitochondria

Move the ten gram weight on the balance beam over two places so exactly 20 grams of water can be added to the test tube.

10 g

Cut the top off of a plastic water bottle and throw the top away.

Step 1

Mass the bottle on a balance beam scale and record.

Step 2

Place 3 teaspoons of baking soda (NaHCO3) in the container

Step 3

Step 8

mass of this minus mass of this

gives the mass of the vinegar used (record)

Step 9

The mass of just the baking soda

Plus

The mass of just the vinegar

Equals

The total mass of the starting reactants.

(record)

plus

Step 10

Slowly pour the vinegar into the container containing the baking soda. Slowly, because if it fizzes over the side you need to start the experiment over again!

Step 11

Slowly swirl the container and solution until all the bubbles and fizz disappears.

Measure out approximately 300 mL of water into the cup.

Mass out the cup and water and record.

Take the temperature of the water and record.

Pour the Urea into the water.

Mass out about 30 g of Urea in weigh boat.

Then mass out the combined mass of the Urea and the weigh boat. Record.

Take the temperature of the Urea (as best as you can) and record.

Slowly add salt with a lab spoon until there is exactly 10 grams of salt in the test tube.

10 g

Move the ten gram weight on the balance beam over two places so exactly 20 grams of water can be added to the test tube.

10 g

Step 10

If you use all 60 mL of the 0.05 M NaOH solution that you have in the syringe and the mystery solution is still not pink, pull up another 60 mL of the 0.05 M NaOH solution and continue.