Because the reactants react with each other and chemically react to produce a different product like with fire when it reacts with the wood it burns and the product left behind is a new different substance from the reactants in this case the product is ash
Explanation:
The nomenclature of ionic compounds is given by:
1. Positive is written first. And if the metal atom has various oxidation states then its oxidation state is to be mentioned in brackets with help of roman numbers
2. The negative ion is written next and a suffix is added at the end of the negative ion. The suffix written is '-ide'.
1.) : Calcium chloride (Correct)
In the given compound, calcium has oxidation state of +2 and chlorine has oxidation state of -1.The name is correct.
2.) : Copper (II) oxide (Incorrect)
In the given compound,copper has the oxidation state of +1 and oxygen has oxidation state of -2.So ,the correct name will be Copper (I) oxide.
3.) : Lead (II) sulfide (Incorrect)
In the given compound, lead has the oxidation state of +4 and sulfur has oxidation state of -2. So ,the correct name will be Lead (IV) sulfide.
Here's my best guess
the volume of the unit cell is (385*10^-12)^3=5.7066*10^-29 m^3
multiply by density to get mass
mass = (7 g/cm^3)*(100^3 cm^3 / 1^3 m^3) * 5.7066*10^-29 m^3= 3.99466*10^-22 g
covert to moles
3.99466*10^-22 g * 1 mol / 239.82 g = 1.6657 *10^-24 mol
convert to number of units
1.6657 *10^-24 mol * 6.23*10^23 units/mol = 1.04
385 pm = 3.85*10^(-8) cm
The volume of the unit cell is the cube of that, which is 5.71*10^(-23) cm^3. Since the ratio of mass to volume (i.e. the density) must be the same no matter what amount of TlCl you have, you can say:
7 = x/(5.71*10^(-23)), where x is the mass of the unit cell. Solving for x, you get 4*10^(-22) g.
The mass of a molecule of TlCl is 240 amu, which in grams is 4*10^(-22) g. The mass of the unit cell and the mass of a molecule of TlCl is the same. Therefore there is one formula unit of TlCl per unit cell.
Scientist rely on their estimates when they cannot obtain on exact numbers
