Volume of a sphere is (4/3)*pi*r^3. how can i calculate the density of a pure gold sphere with a given ?
2. The density of aluminum is 2.70 g/cm^3. Calculate the thickness of a rectangular sheet of aluminum foil with a width of 11.5cm, a length of 14.0 cm, and a mass of 2.04g.
3.We estimate to 1/10 or 2/10 of the smallest division on any instrument to obtain the final significant digit in a measurement. State the magnitude of the smallest division, and give the units, for the following instruments:
ruler: mm
buret:mL
Graduated cylinder: mL
and how can i find analytical balance? thx a lot!
Answer:
1.
mass = 94.19 g
volume = 4/3 x pi x r^3 = 4/3 x 3.14 x (2.120 cm / 2) ^ 3
= 4/3 x 3.14 x (1.06 cm)^3 = 4.986 cm^3
density = mass / volume = 94.19 g / 4.986 cm^3 = 18.89 g/cm^3
2.
volume = length x width x height = 11.5 cm x 14.0 cm x H
= 161 cm^2 x H (if we let H = height)
mass = 2.04 g
density = 2.70 g/cm^3
since density = mass / volume, then volume = mass / density
and
161 cm^2 x H = 2.04 g / 2.70 g/cm^3 = .756 cm^3
so that
H = .756 cm^3 / 161 cm^2 = .00469 cm
3.
1/10 of mm = .1 mm = 100 micrometers
1/10 of ml = .1 ml = 100 microliters
analytical balances range from +/- 0.0001 grams to +/- kg's
0.0001 gram = 100 micrograms
density is mass per unit volume. not that hard, dude.
cant you find density or mass with a beaker and water, then calulating the difference when you put the object in?
just trying to help.im only in ninth grade
1)Density (D) is mass (M) per volume (V). A common mass unit is the gram. A common volume unit is the cubic centimetre. Plug and chug babe. Also, fyi: 1 mL~1cm^3~1 g (based on water, god bless the System International!)
2) This is a flip of the last one.
D=M/V V=l x w x h
(g/cm^3)=(g)/(cm x cm x cm)
(2.70)=(2.04)(11.5 x 14.0 x w)
Solve for w.
3) 1+/-0.1 mm
1 +/- 0.1 mL
1 +/- 0.1 mL
http://www.vwr.com/index.htm
You might want to reconsider delaying your purchase of an analytical balance until you can do these simple problems.
if density is = to mass/volume then
2.70 g/cm^3= 2.04g/(11.5cm*14.0cm*Wcm)
so
(11.5cm*14cm*Wcm)= 2.04g/2.70g/cm^3
therefore
W= 0.755... cm^2 /161cm^2
which is
4.693 *10^-3cm
just keeping it simple
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