Lab Equipment/Separation Activities #3

Lab Equipment/Lab Activities #3

Day 4 Boiling/Evaporating the Salt-Water Solution to retrieve the Salt

*I can set up the hot plate to prepare to boil away water.

*I can use evaporating dish and watch glass to boil away the water over a flame to get the salt.

Separation of Sand, Salt and Iron

• IRON has been removed with a magnet and weighed (Day 1)

• We measured water in a buret and in a graduated cylinder (Day 2)

• SAND has been filtered from the salt solution and is on filter paper. (Day 3)

• Once the filter paper and sand dry overnight, the sand is weighed.

• Next....

• We are ready to retrieve the SALT that is in the water. We would call this our SALT SOLUTION. (Day 4)

SET UP FOR BOILING/

EVAPORATING LIQUID

• Hot plate

• Evaporating Dish

• Watch Glass

SET UP FOR BOILING/

EVAPORATING LIQUID

• Ring Stand

• Iron Ring

• Wire Gauze

• Bunsen Burner

• Evaporating Dish

• Watch Glass

This is the SET UP for a lab having
GAS and Bunsen Burners

Evaporating Dish

Watch Glass

Evaporating Dish - made of porcelain so it can be heated

Watch Glass - clear concave shaped glass used as a cover. [Looks like a huge contact lens...LOL]

Boiling Away the Liquid (Evaporation)

Salt solution was added to the evaporating dish.

Flame was used to heat and boiling of the liquid begins.

This should be done slowly as to not boil over or lose any salt in the solution.

Note we haven't put the watch glass on when boiling begins. We will add that toward the end of boiling.

Boiling Away the Liquid (Evaporation)

Toward the end of boiling the salt will begin to pop out as it gets less liquid.

To keep from losing salt we will add the watch glass over the crucible.

Note he is using crucible tongs to pick up and place the watch glass. That's because the evaporating dish is HOT and it's the best way.

Boiling Away the Liquid (Evaporation)

Once boiling is finished, this is what the SALT looks like.

Note it looks crusty, but white and it is definitely salt.

Using balance the weigh the SALT

The evaporating dish and watch glass crusted with white SALT is taken to the electronic balance and the mass is weighed in GRAMS (g).

To get the mass of just the SALT, we have to SUBTRACT the mass of the evaporating dish and watch glass.

Multiple Choice

Students working on a separation lab like we performed in class boiled away water and obtained the following. What is the residue left behind?

• sand

• ash

• salt

• iron

Multiple Choice

A student weighed their evaporating dish, watch glass crusted with salt and recorded this data:

Mass of evap dish, watch glass & salt: 176.74 g

Mass of evap dish and watch glass: 162.51 g

What is the mass of just the SALT?

^{(Do you know what to do? Hint: SUBTRACT)}

• 15.52 g

• 160.74 g

• 14.23 g

Multiple Choice

Which of the following would be used to boil away water?

Multiple Choice

Identify the equipment shown here:

• crucible

• evaporating dish

• mortar and pestle

• bowl

Multiple Choice

To prevent boiling liquid and materials from popping out you may use which of the following?

Multiple Choice

This item is used on an iron ring and beakers or dishes can sit on them and safely be heated.

Multiple Choice

Identify the equipment shown here:

• concave glass

• convex glass

• watch glass

• glass plate

Multiple Choice

Identify the equipment shown here:

• test tube holder

• iron rod

• iron ring

• ring stand

TONGS - 2 different types

Beaker Tongs

*Note the wide gap big enough to hold or pick up a beaker

*Beaker Tongs can be coated with black or can be plain metal

TONGS - 2 different types

Crucible Tongs

*Note the smaller gap at the end and tips that meet

*This is for handing smaller HOT objects.

Crucible Tongs

See the crucible tongs holding the small porcelain crubible.

Crucible Tongs

Another pic showing small porcelain crucible and crucible tongs

Multiple Choice

• scoopula

• dropper

• crucible tongs

• beaker tongs

Multiple Choice

What is this piece of lab equipment?

• forceps

• tweezers

• beaker tongs

• crucible tongs

Multiple Choice

What is this?

• thermometer

• glass stirring rod

• buret

• beaker

Multiple Choice

Identify the equipment shown here:

• wire gauze

• flame spreader

• sieve

• mesh

KNOW YOUR FLASKS

Erlenmeyer Flask = triangular shaped

Florence Flask (a.k.a. round bottom flask) = round bottom shaped

Erlenmeyer Flasks

It is named after the German chemist Emil Erlenmeyer (1825–1909), who created it in 1860. 

Erlenmeyer flasks have wide bases, with sides that taper upward to a short vertical neck

Florence Flask

A Florence flask (also known as a round bottom flask or a boiling flask) is a piece of laboratory glassware. It is a round or flat-bottom flask with a long neck.

The flask is named after Florence, Italy.

Wrap Up and Complete Calculations from Sand, Salt and Iron Separation Lab

• Percent by Mass Calculations

• What % IRON was in the sample? What % SAND was in the sample? What % SALT was in the sample?

• % Mass = mass of that part/total mass of the mixture x 100

• If students performed perfect lab techniques and didn't lose any part or make any mistakes, then the 3 percentages would add to = 100%

Let's practice doing % Mass IRON

• Lab data: mass of original mixture of sand, salt & iron = 32.45 g

• Lab data: mass of iron = 6.75 g

• % Mass = 6.75 g/32.45 g x 100 =

• Use calculator DIVIDE first two numbers, then times by 100, then enter

• Ok...go to next slide. Let's see what you got!!!

Multiple Choice

Using a calculator do this calculation:

% Mass IRON = 6.75 / 32.45 x 100 = ??

Use calculator DIVIDE first two numbers, then times by 100, then enter

• 6.75%

• 20.8%

• 28.0%

• 480.7%

Let's practice doing % Mass SAND

• Lab data: mass of original mixture of sand, salt & iron = 32.45 g

• Lab data: mass of sand= 17.62 g

• % Mass = 17.62 g/32.45 g x 100 =

• Use calculator DIVIDE first two numbers, then times by 100, then enter

• Ok...go to next slide. Let's see what you got!!!

Multiple Choice

Using a calculator do this calculation:

% Mass SAND= 17.62 g/32.45 g x 100 =

Use calculator DIVIDE first two numbers, then times by 100, then enter

• 17.62%

• 50.1%

• 54.3%

• 184.2%

Let's practice doing % Mass SALT

• Lab data: mass of original mixture of sand, salt & iron = 32.45 g

• Lab data: mass of sand= 8.08 g

• % Mass = 8.08 g/32.45 g x 100 =

• Use calculator DIVIDE first two numbers, then times by 100, then enter

• Ok...go to next slide. Let's see what you got!!!

Multiple Choice

Using a calculator do this calculation:

% Mass SALT= 8.08 g/32.45 g x 100 =

Use calculator DIVIDE first two numbers, then times by 100, then enter

• 8.08%

• 40.5%

• 54.3%

• 24.9%

Multiple Choice

When you add the 3 percentages you just calculated and add them.

20.8% Iron

54.3% Sand

24.9% Salt

What is the total percent when you add?

• 100%

• 95%

Multiple Select

Rarely does lab work go perfectly. What possible reasons might account for a student who gets 96.5% total percent instead of 100%? ^{[Mark all that apply.]}

• Spilled some sample on lab table

• Knocked over their salt solution in flask and lost some salt

• Some sand wouldn't come out of the beaker and stuck to the side and didn't get filtered

• While using magnet, some iron filings were small and fell in the floor

Revisit Measuring

• Don't forget to look at bottom of meniscus when measuring volume of liquids

• Note how the instrument is marked off...is it by 1's or by 0.1's or by 5's, etc...

• If a level is "between" two values it is correct to estimate the last number.

Estimating the Last Number when measure isn't perfect

• Note the bottom of this meniscus is "between" two marks

• Note this cylinder is marked off by 1's. Each mark is 1 unit.

• So the volume is "between" 25 ml and 26 ml

Estimating the Last Number

• So....this is up to each person to estimate the number 0.1 to 0.9

• So do you think it's halfway between? If so, 25.5 ml

• Or do you think it's higher up than halfway? If so, 25.6 ml or 25.7 ml or 25.8 ml or 25.9 ml would ALL be reasonable!!!!!

• ANY of these is acceptable since this is an estimate!

Multiple Choice

Water pulls up on sides of glass tubes forming a curve known as a ___________.

• meniscus

• bubble curve

• watch glass

• graduated curve

Multiple Choice

If you were measuring this liquid and believed it to be right on a perfect mark, what would be your reading?

• 20.1 ml

• 20.0 ml

• 19.0 ml

• 21.0 ml

Multiple Choice

What is the BEST volume measurement you could record for this graduated cyclinder?

• 24.0 mL

• 24 mL

• 23.7 mL

• 23 mL

Multiple Choice

What is the BEST volume measurement on this graduated cylinder?

• 50.3 ml

• 53 ml

• 52.9 ml

• 57.9 ml

Multiple Choice

Which is the best temperature reading you can record on this thermometer?

• 23 ^oC

• 22.5 ^oC

• 24 ^oC

• 23.1 ^oC

Multiple Choice

Looking carefully, what is the best reading you could record for temperature on this thermometer?

^{(NOTE: temperatures can be below zero, but below zero you are counting DOWN.)}

• -7.0

• -3

• -3.0

• -2.8

Multiple Choice

Describe the process shown here.

• chromotagraphy

• boiling/ evaporation

• filtration

• using a magnet