Answer:
History of composition
Years Material Weight (grains)
1944–1946 gilding metal (95% copper, 5% zinc) 48 grains
1947–1962 bronze (95% copper, 5% tin and zinc) 48 grains
1962 – September 1982 gilding metal (95% copper, 5% zinc) 48 grains
October 1982 – present copper-plated zinc (97.5% zinc, 2.5% copper) 38.6 grains
Take the 72 g and divid it by 6 which would equal 12 g each
Formula mass, molar mass and Avagadro's number.
Explanation:
number of atoms in a compound can be calculated by knowing the molar mass of the compound or element, the result will be multiplied by avagadro's number (6.022*10^23)
1 mole of a substance is equal to Avagadro number of atoms.
If the number of moles is known of a compound or element its molar mass can be calculated as:
n= Weight of the compound/element given/ molecular weight of the same.
formula mass is the mass of compound ie chemical compound formed with different molecules. its mass is calculated by adding the molar masses of all the elements taking part in its assembly.
<span>1 ml of water weighs 1 gram so 1 liter (1000 ml) weighs 1000 grams. A 3% solution (3% = 0.03) of hydrogen peroxide (w/v) would contain 1000 grams x 0.03 or 30 grams. The chemical formula of hydrogen peroxide is H2O2 and a mole weighs 34.0147 grams/mole. So 30 grams of H2O2 divided by 34.0147 grams/mole equals 0.88 moles of H2O2. The concentration of a 3% (w/v) hydrogen peroxide solution therefore contains 30 grams of H202 (or 0.88 moles of H202) per in a liter of water (or 1000 grams H20) would thus be 0.88 moles H2O2 per liter (0.88 moles H2O2/l) .</span>