In the laboratory a student uses a "coffee cup" calorimeter to determine the specific heat of a metal.

she heats 19.5 grams of tungsten to 97.80°c and then drops it into a cup containing 78.3 grams of water at 22.58°c. she measures the final temperature to be 23.20°c.

assuming that all of the heat is transferred to the water, she calculates the specific heat of tungsten to be j/g°c.

Answer : The specific heat of tungsten is,

Explanation :

In this problem we assumed that heat given by the hot body is equal to the heat taken by the cold body.

where,

= specific heat of tungsten = ?

= specific heat of water =

= mass of tungsten = 19.5 g

= mass of water = 78.5 g

= final temperature =

= initial temperature of tungsten =

= initial temperature of water =

Now put all the given values in the above formula, we get

Therefore, the specific heat of tungsten is,

the grams   of   barium that   are in   2.3 x 10^23   atoms of barium   is   52.4 g (answer c)

    calculation

mass = moles   of ba   x molar   mass of ba

  molar mass of ba from periodic table=   137.3 g/mol

  use the   avogadro's law   constant   to   calculate the moles of barium

  that   is     1 mole =   6.02   x 10^23 atoms

                    ? moles = 2.3 x 10^23   atoms

by cross   multiplication

=(1 mole   x 2.3x 10^23 atoms)   / 6.02   x10^23 atoms)=   0.382   moles

mass   is therefore = 137.3   g/mol x 0.382 mol = 52.4 ( answer c)

explanation:

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-