Answer:
20.2 kJ
Explanation:
Based on the information in the reaction, the amount of heat released per mole of Na₂O₂ (the molar enthalpy) is calculated as follows:
126 kJ / 2 mol = 63 kJ/mol Na₂O₂
The number of moles in 25.0g of Na₂O₂ must be calculated using the molecular weight of Na₂O₂ (77.978 g/mol):
(25.0 g)/(77.978 g/mol) = 0.32060 mol Na₂O₂
Thus, the heat released will be:
(63 kJ/mol)(0.32060 mol) = 20.2 kJ
Answer: Atomic mass of gallium = 69.72304093 amu
Explanation:
We calculate the atomic mass of Gallium by using the Relative abundance of the isotopes.
Atomic mass =mass x Natural Abundance of Isotope 1 +mass x Natural Abundance of Isotope 2
(60.11/100 x 68.9256) + (39.89/100 x 70.9247)
= 41.43117816 + 28.29186283 = 69.72304093 amu
Answer:
<h2>1.806 × 10²³ atoms</h2>
Explanation:
The number of sodium atoms can be found by using the formula
<h3>N = n × L</h3>
where n is the number of moles
N is the number of entities
L is the Avogadro's constant which is
6.02 × 10²³ entities
From the question we have
N = 0.3 × 6.02 × 10²³
We have the final answer as
<h3>1.806 × 10²³ atoms</h3>
Hope this helps you
Pb/pbco3*100
207/207+12+48
207/267*100
=77.53%
