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The British gold sovereign coin is an alloy of gold and copper having a total mass of 7.988 g, and is 22-karat gold.

(a) Find the mass of gold in the sovereign in kilograms using the fact that the number of karats = 24× (mass of gold)/ total mass.

(b) Calculate the volumes of gold and copper, respectively, used to manufacture the coin.

(c) Calculate the density of the British sovereign coin.

Answer :

sebassandin

Answer:

(a) [tex]m_{gold}=7.322g[/tex]

(b)

[tex]V_{gold}=0.379cm^3[/tex]

[tex]V_{copper}=0.122cm^3[/tex]

(c) [tex]\rho _{coin}=15.94g/cm^3[/tex]

Explanation:

Hello,

(a) In this case, with the given formula we easily compute the mass of gold contained in the sovereign  as shown below:

[tex]m_{gold}=\frac{m_{tota}*karats}{24}=\frac{7.988g*22}{24}=7.322g[/tex]

(b) Now, by knowing the density of gold and copper, 19.32 and 8.94 g/cm³ respectively, we compute each volume, by also knowing that the rest of the coin contains copper:

[tex]V_{gold}=\frac{m_{gold}}{\rho_{gold}} =\frac{7.322g}{19.32g/cm^3}=0.379cm^3[/tex]

[tex]m_{copper}=7.988g-7.322g=1.09g\\V_{copper}=\frac{m_{copper}}{\rho_{copper}}=\frac{1.09g}{8.94g/cm^3} \\\\V_{copper}=0.122cm^3[/tex]

(c) Finally, the volume is computed by dividing the total mass over the total volume containing both gold and copper:

[tex]\rho _{coin}=\frac{m_{total}}{V_{gold}+V_{copper}}=\frac{7.988 g}{0.379cm^3+0.122cm^3}\\ \\\rho _{coin}=15.94g/cm^3[/tex]

Best regards.

Answer:

a

The mass of gold is  [tex]L = 7.322 *10^{-3} \ kg[/tex]

b

     The volumes of gold and copper is  [tex]V_g = 3.794 *10^{-7} \ m^3[/tex]  , [tex]V_c = 7.426 *10^{-8} \ m^3[/tex]

c

      The density of the British sovereign coin

          [tex]\rho = 17.593*10^{3} \ kg/m^3[/tex]

Explanation:

From the question we are told that

    The total mass of the gold is  [tex]K = 7.988 \ g = 7.988 * 10^{-3} \ kg[/tex]

      The karat of the British gold sovereign is  [tex]z = 22[/tex]

     

Let the mass of gold in the alloy be  L  

Now we are told that

       [tex]z = 24 * \frac{L}{K}[/tex]

substituting value  

        [tex]22 = 24 * \frac{L}{7.988 * 10^{-3}}[/tex]

  So  [tex]L = \frac{22}{24} * 7.899*10^{-3}[/tex]

        [tex]L = 7.322 *10^{-3} \ kg[/tex]

The volume of the gold coin is  mathematically represented as

         [tex]V_g = \frac{L}{\rho_g }[/tex]

Where   [tex]\rho_g[/tex] is the density of the gold which a constant with value  

     [tex]\rho_g = 19.3 *10^{3} \ kg /m^3[/tex]

So

         [tex]V_g = \frac{7.322 *10^{-3}}{19.3 *10^{3} }[/tex]

         [tex]V_g = 3.794 *10^{-7} \ m^3[/tex]

The mass of copper is mathematically evaluated as

        [tex]m_c = K - L[/tex]

        [tex]m_c = 7.988*10^{-3} - 7.322 *10^{-3}[/tex]

        [tex]m_c = 6.657 *10^{-4} \ kg[/tex]

Volume of the copper is  

          [tex]V_c = \frac{m_c}{\rho_c}[/tex]

Where   [tex]\rho_c[/tex] is the density of the copper which a constant with value  

        [tex]\rho_c = 8.92 * 10^{3} \ kg/m^3[/tex]

So

       [tex]V_c = \frac{6.657 *10^{-4}}{8.92 *10^{3}}[/tex]

       [tex]V_c = 7.426 *10^{-8} \ m^3[/tex]

The total volume of the British gold sovereign coin is  \

        [tex]V = V_g + V_c[/tex]

substituting values

        [tex]V = 3.7939 *10^{-7} + 7.4626 *10^{-7}[/tex]

        [tex]V = 4.54 *10^{-7} \ m^3[/tex]

The density of the British gold sovereign coin is

      [tex]\rho = \frac{K}{V}[/tex]

substituting values

         [tex]\rho = \frac{7.988 *10^{-3}}{4.54 *10^{-7}}[/tex]

         [tex]\rho = 17.593*10^{3} \ kg/m^3[/tex]

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