Science problems....mom and dad can't help me :[[?

Question

okay i dont want just the answer.
thats not what im looking for.
i just need help to know how to do it.

1.) Find the density of a substane that has a mass of 45 kg and a volume of 43m3(meters cubed). (Hint: Make sure your answer's units are units of density.)
[[the answer i got was D=45kg/43m3=1.04kg/m3]]

2.)Suppose you have a lead ball whose mass is 454 g. What is the ball's volume?

3.)What is the mass of a 15mL sample of mercury?




please help me...my mom and dad don't know how to do it...and we have a 3 day weekend....thanks :]]

okay i got a lot of good sudjestions and help. :]] thanks a bunch. now i just need to know if i did it right. sence number one was correct...

2.)Suppose you have a lead ball whose mass is 454g. What is the ball's volume?
[[i got the answer of, V=454g/11.35g per cm3=40g/cm3]]

3.) What is the mass of a 15 mL sample of mercury?

[[i got the answer of..M=13.55g per cm3/15mL=.90mg per cm3]]


please let me know if that is correct. :]] thanks a bunch...

you have no idea how hard it is to learn anything from this teacher so we are like forced to try and learn it with no idea of how to do the assignment on our own..

Answer 1

The relationship you need is that mass / volume = density.

Your answer to (1) is correct.

For (2), look up the density of lead in your textbook. Convert the mass to kg if necessary, and divide mass by density to get volume.

For (3), look up the density of mercury in your textbook. Convert mL to cubic centimeters or cubic meters and multiply the volume by the density to get mass.

Answer 2

You need to know the density of lead and mercury to find the last 2. Then it's just simple maths!

PS: The first one is correct.
PPS: 1ml = 1cm^3

Edit: For question 2, the answer will be in cm^3 or m^3 for volume.
For question 3 the answer will be in kg or g for mass.

Answer 3

Density is defined as mass per unit volume. For each of these questions, all you need to do is set up our units correctly.

1) Your answer is correct. Congratulations.

2) a) If D = M/V, then by algebra V = M/D.
b) look up the density of lead through this link: http://environmentalchemistry.com/yogi/periodic/density.html
c) divide mass in grams by density in grams per volume to obtain volume.

3) If D = M/V, then M = D / V.
a) Look up density of mercury in same table.
b) divide density in grams per quoted volume, by given volume properly converted to quoted volume.

In your homework, be sure to cite the webpage as your source.

Good Luck!

Answer 4

For 1, you did well.

For 2, you need to find out the density of lead.

For 3, you need to find out the density of mercury.

Answer 5

Plug the variables into the equation (d = m/v).