You have a piece of gold jewelry weighing 9.35g. Its volume is 0.654cm 3 . Assume the metal is an alloy of gold and silver, which have densities of 19.3g/cm 3 and 10.5g/cm 3 , respectively. Also assume that there is no change in volume when the pure metals are mixed. Calculate the percentage of gold (by mass) in the alloy.

57.54% is the percentage of gold by mass in the alloy.

Explanation:

The mass of the mixture is 9.35g. That is:

9.35g = Mass Gold + Mass Silver

Mass silver = 9.35g - Mass gold (1)

Now, the volume of the jewelry is the sum of volumes of gold and silver:

0.654cm³ = Mass Gold / 19.5g/cm³ + Mass silver / 10.5g/cm³ (2)

Volume = Mass / Density.

Replacing (1) in (2):

0.654cm³ = Mass Gold / 19.5g/cm³ + (9.35g - Mass gold) / 10.5g/cm³

0.654 = 0.051282 Mass Gold + 0.890476 - 0.095238 Mass gold

-0.236476 = -0.043956 Mass gold

Mass gold = 5.38g

And mass percent of gold in the alloy is:

5.38g / 9.35g * 100 =

when the volume of gas is   changed from   717.73 ml   to 852 ml   the temperature will   change   from 315   c to 452   c

    calculation

this is calculated using the charles law formula

that is,   v1/t1 = v2/t2

          v1=?

        t1 = 315 c   into   kelvin = 315 +273 = 588 k

        v2 = 852   ml

        t2 = 425c + 273 =698 k

make v1   the subject of the formula ( by   multiplying both side by t1)

  v1=( v2 xt1) / t2

v1= (852 ml   x 588 k)/ 698 k= 717.73 ml