What is the density of an 81.2 g sample of
an unknown substance if the sample occupies
49.2 cm3? Answer in units of g=cm3.
What volume would be occupied by 8.1 g of
a substance with a density of 1.65041 g=cm3?
Answer in units of cm3.
2006-09-11 15:06:07 · 4 answers · asked by sarahmadison87 1 in Science & Mathematics ➔ Chemistry
The basic formula to remember is that mass = density x volume.
In your first question, you know mass and volume so solve the above for density:
density = mass/volume
Similarly in the second question. solve for volume:
Volume = mass/density.
In each case the number of significant figures in the answer should not be more than those in the factor with the lowest number of significant figures. In the first example, each factor (density and volume) both have three significant figures, and that is what the result should contain. So in the first example, the answer should be 1.65 gm/cm^3, even though you could calculate it out much further.
In the second example, the volume is given in only two significant figures, while the density is given in 6. This means the result should only have two significant figures. However, in making the calculation, it is always a good idea to use all the significant figures you have available in the factors, and round off after you get the result. So the result is 4.90787....cm^3, but the answer should be written 4.9 cm^3.
For more information on handling significant figures, see
http://en.wikipedia.org/wiki/Significance_arithmetic
2006-09-11 15:19:23 · answer #1 · answered by gp4rts 7 · 0⤊ 0⤋
Density should be in g/cm3. All you do is divide the mass by the volume. Mass is in grams, volume is in cm3.
2006-09-11 15:15:52 · answer #2 · answered by perioligament 4 · 0⤊ 0⤋
omg i am in the same **** lol
but i am sorry i dont' know i hate this crap! i would like to know also
2006-09-11 15:10:11 · answer #3 · answered by thisgrrllovespurple 2 · 0⤊ 0⤋
1.65g/cm3
2006-09-12 01:28:38 · answer #4 · answered by Brandon D 1 · 0⤊ 0⤋