chemistry density question please help!?

Question

i have no idea how to do these 2 problems and i have one more try to get them right because its online. i need your help!

The density of aluminum is 2.70 g/cm3. A square piece of aluminum foil, 8.0 in. on a side, is found to weigh 2.575 g. What is the thickness of this foil, in millimeters?

and

The accompanying illustration shows a 100.0 mL graduated cylinder half-filled with 6.8 g of diatomaceous earth, a material consisting mostly of silica and used as a filtering medium in swimming pools. How many milliliters of water are required to fill the cylinder to the 100.0 mL mark? The diatomaceous earth is insoluble in water and has a density of 2.2 g/cm3.

thanks in advance for any help i really appreciate it!

Answer 1

First one:
Find the volume of the aluminum in the sample: (You can estimate it will be close to 1cm3 because its mass is close to 2.7g)

2.575g/2.70g/cm3 = 0.9537cm3

Now convert units for size:

8" x 2.54cm/in = 20.32cm

Remember, the volume of the sample (0.9537cm3) is just LxWxH; its 3 different dimensions multiplied (and you already have 2), so you can easily find the last one:

0.9537cm3 = 20.32cm x 20.32cm x "thickness"

Dividing both sides by the quantity: 20.32cm x 20.32cm gives:

0.9537cm3/[20.32cm x 20.32cm] = 0.00231cm or 0.0231mm
(Remember they wanted MILLIMETERS!)

For the second one:

You need to find the actual volume occupied by the diatomaceous earth particles without including any pore spaces between. It's 6.8g/2.2g/cm3 = 3.1 cm3

So water needed is: 100 - 3.1 = 96.9ml (remember 1 ml = 1 cm3)

Answer 2

Question #1
What you are solving for is the volume of Al foil that you have. You are given 2 of the dimensions, the density and the weight of the Al. All you need to do is:

Volume X Density = mass
(Side A X Side B X Thickness) = Volume of Al

8 in = 20.32 cm so --> (20.32)^2 (thickness) X 2.70 g/cm3= 2.575 g. Just solve for thickness in cm units

Question 2:

First figure out the volume that the diatomaceous earth should occupy: 6.8 g / 2.2 g/cm3 = volume of Dia earth, then just subtract this from 100 ml to get the amount of water needed.

Answer 3

interesting difficulty! Density is defined using fact the mass of a substance in line with unit quantity. In different words, divide mass by making use of quantity. in this difficulty cm3 skill cubic centimeter. a million cm3 is a unit of quantity. For this difficulty, divide 234 g by making use of seven.nine cm3 to get 29.sixty two g/cm3. ask your self the place the rock got here from--it did not come from Earth. The densest time-honored substance in the worldwide at huge-unfold situations of a million environment and 25°C is the ingredient osmium (Os). It has a density of twenty-two.57 g/cm3.