Answer:
157.79 g
Explanation:
The definition of molality is:
- molality = moles of solute / kilogram of solvent
This means that in a 2.7 molal solution, there are 2.7 moles of NaCl per kilogram of water.
So now w<u>e convert those 2.7 moles of NaCl to grams</u>, using its <em>molar mass</em>:
- 2.7 mol * 58.44 g/mol = 157.79 g
We know that the element Z = 119 would be placed right below the Fr, in the column of the alcaline metals.
We also know that the trend in the electronegativity is to decrease when you go up-down ia group.
The known electronegativities of the elements of this group are:
Li: 0.98
Na: 0.93
K: 0.82
Rb: 0.82
Cs: 0.79
Fr: 0.70
Then the hypotetical element Z = 119 would probably have an electronegativity slightly below 0.70, for sure in the range 0.60 - 0.70.
Answer:
1.2 x 10⁵ moles Ag (2 sig. figs.)
Explanation:
1 mole any substance (elements or compounds) => 6.023 x 10²³ particles of specified substance
∴ 6.9 x 10²⁸ atoms Ag = 6.9 x 10²⁸ Ag atoms / 6.023 x 10²³ Ag atoms/mole Ag
= 1.145608501 x 10⁵ moles Ag (calculator answer)
= 1.2 x 10⁵ moles Ag (2 sig. figs.)
