Answer:
the properties of three undiscovered elements is the correct answer.
Explanation:
After he completed his work Mendeleev predicted the properties of the undiscovered elements.
In the year 1871, Dmitri Mendeleev predicted the detailed existence and the properties of the three elements that are undiscovered and he gained tremendous fame.
He left the gap in the table to put the elements which are not identified at that time and by glancing at the physical and chemical properties of an element next to the gap, Mendeleev could predict the properties of the not discovered elements.
the cathode is where reduction occurs!
We subtract the enthalpies of the reactants from that of the products:
Since this is < 0, this is an exothermic reaction.
Answer:
Mass of sodium chloride decomposed = 24.54 g
Explanation:
Given data:
Mass of sodium chloride decomposed = ?
Mass of chlorine gas formed = 15 g
Solution:
Chemical equation:
2NaCl → 2Na + Cl₂
Number of moles of Cl₂:
Number of moles = mass/molar mass
Number of moles = 15 g/ 71 g/mol
Number of moles = 0.21 mol
Now we will compare the moles of Cl₂ with NaCl from balance chemical equation.
Cl₂ : NaCl
1 : 2
0.21 : 2×0.21 = 0.42 mol
Mass of Sodium chloride decompose:
Mass = number of moles × molar mass
Mass = 0.42 mol × 58.44 g/mol
Mass = 24.54 g
