1. why is it important to heat the baking dish or ramekin and cover in step #1?
2. why is it necessary to achieve constant mass? how will you know when constant mass is achieved?
3. why should the ramekin be cooled before taking a mass reading?
4. how might each of the following affect the reliability of your results? explain.
• increased humidity in the room.

• eliminating the preliminary heating, cooling, and massing of the ramekin and cover prior to its use.
(step 1)
• measure the mass of a clean, dry baking dish with the cover. record the mass of the empty, dry dish and cover in data table entry #1. place a clean, dry baking dish or ramekin with the cover ajar in the oven and heat for 10 minutes at 250◦f. discontinue heating and carefully use hot pads to remove the dish and cover onto a cooling rack for cooling. when cool enough to touch (about 5 minutes), measure the mass of the dish and cover. record the mass of the empty, dry dish and cover in data table entry #2.

1. A hydrated salt is a salt that has a crystalline molecular structure and is loosely attached to water molecules, hence “hydrated” in the name. On the contrary, an anhydrous salt with no water for hydration. When breaking up the word “anhydrous” we see that “an” means it is without and the “hydrous” tells us it is without water.

2. It is important to heat the baking dish or ramekin to achieve a constant mass with two consecutive masses that differ no more than 0.1g.

3. It is necessary to achieve constant mass to accurately measure the salts and hydrates that are used in the lab. You will know you have obtained a constant mass when two consecutive masses differ by no more than 0.1 g.

4. The ramekin should be cooled before taking a mass reading because the heat could have an effect of the mass of a specific substance.

5a. The increased humidity could potentially affect the hydrated salt and the hydrate used in the lab, which would cause inconsistencies in the data table.

5b. Without the heating of the ramekin in the preparation for the lab, a constant mass wouldn’t be achieved and would affect the measurement of the substance’s masses.

5c. It could affect the accuracy of the measurement and the reliability that the measurement is true to the fullest extent.

Explanation: PLEASE PUT INTO YOUR OWN WORDS!

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.

no, the red giant is the hottest with 2.00.000.000 degrees celsius. while the white dwarf only 25,000 degrees celsius.