Answer:
A. 0.295 mole
B. 0.055 mole
C.0.144 mole
D. 0.03 mole
Explanation:
To find the amount in moles, we simply use a mathematical relation that connects mass, atomic mass and number of moles.
Number of moles = mass/atomic mass
A. Atomic mass of Argon is 40
n = 11.8/40 = 0.295 mole
B. Atomic mass of zinc is 65
n = 3.55/65 = 0.055 mole
C. Atomic mass of Tantalum is 181
n = 26.1/181 = 0.144 mole
D. Atomic mass of lithium is 7
n = 0.211/7 = 0.03 mole
Answer: No
Explanation:
- Law of definite proportions is a case from the Law of conservation of energy (matter) which states that "mass can neither be created nor destroyed, but changed from one form to another."
- Adding coefficients to a chemical equation confirms that there is the same number of atoms on both sides of a reaction; therefore, matter has not been created or destroyed but reorganized to give new substrates.
Example : 2 Mg + O2 → 2 MgO
In the balanced equation above, 2 moles of Mg reacts with 1 mole of O2 to produce 2 moles of MgO.
mass of 2 moles of Mg = 24×2= 48 grams
mass of 1 mole of O2 = 16+16 = 32 grams
total mass of reactants = 48 + 32 = 80 grams
mass of 2 moles of MgO = (24+16) ×2 = 80 grams
total mass of products = 80 grams
It is clear that the number of grams of matter before and after the reaction is the same and equals to 80 grams, so obeys the law of definite proportions..
I believe B) in both chemical changes and physical changes since in chemical changes, nothing is created or destroyed. In physical changes same thing but with matter.
Ar is a substance that is a gas at room temperature and atmospheric pressure.
The (II) is a roman numeral indicating the oxidation number of a transition metal. It is used when you refer to the element/compound by name but does not show up in the formula.
