Answer:
66.7 g
Explanation:
Number of atoms = 2×10²¹
Mass of 2×10²¹ atoms = 0.4 g
Mass of 0.5 moles of that element = ?
Solution:
1 mole contain 6.022×10²³ atoms
2×10²¹ atoms × 1 mol / 6.022×10²³ atoms
0.33×10⁻² mol
0.003 mol
0.003 mole have mass of 0.4 g
0.5 mol have mass 0.5/0.003×0.4 g = 66.7 g
Answer:
Explanation:
1. Please provide the enthalpy info - I will work on it with the info
2.
i) Reaction a should be modified to match the number of S in equation:
2S + 2O2 -> 2SO2 deltaH = -370kJ
ii) Reaction b should be written reversely to match the reactants of SO2:
2SO2 + O2 -> 2SO3 deltaH = 256kJ
iii) Adding the equations together:
2S + 3O2 -> 2SO3
iv) Enthalpy of the combined reaction = -370+256 = -114kJ
It is negative so the reaction is exothermic.
Answer:
See below
Step-by-step explanation:
- Hydrogen either reacts with or is formed by reactions with many other elements, so chemists could use it directly to determine their relative masses.
- Hydrogen has the smallest atomic mass, so it was convenient to give H a relative atomic mass of 1 and assign those of other elements as multiples of this number.
The O = 16 scale became the standard in 1903 and carbon-12 was chosen in 1961.
Answer:
Combination reaction
Explanation:
N2+H2 = NH3
they combine together to form a product
Answer: K only has 1 valence electron. It will leave with only a little effort, leaving behind a positively charged K^+1 atom.
Explanation: A neutral potassium atom has 19 total electrons. But only 1 of them is in potassium's valence shell. Valence shell means the outermost s and p orbitals. Potasium's electron configuration is 1s^2 2s^2 2p^6 3s^2 3p^6 4s^1. The 4s orbital is the only orbital in the 4th energy level. So it has a valency of 1. This means this electron will be the most likely to leave, since it is the lone electron in the oyutermost energy level (4). When that electron leaves, the charge on the atom go up by 1. The atom now has a full valence shell of 3s^2 3p^6, the same as argon, Ar.
