Answer:
0.71
Explanation:
The molecular mass of NaCl is, 23+35.5
= 58.5
1 mole means molecular mass (in gram)
In 58.5 gm NaCl there is 1 mole.
So, 42.1 gm NaCl contains 42.1/58.5 =0.71 moles.
Answer:
If it loses 2 electrons, the net charge on the atom will be 2+
If the atom instead gains 4 electrons, the net charge will be 4-
Explanation:
It is based on adding and subtracting charges. Protons are +1 and electrons are -1
If the atom has 9 protons and 9 electrons, the net charge is +9 + (-9) = 0. The +9 is the 9 protons and the -9 is from the 9 electrons.
If two electrons are taken away, there would be 9-2 or 7 electrons with 9 protons. The net charge would then be +9 + (-7) = +2. +9 comes from the 9 electrons and -7 is from the 7 electrons.
So, if two electrons are taken away, the net charge is +2.
Similarly, if the atom gains 4 electrons, there will be 9+4 or 12 electrons and 9 protons. The net charge would then be +9 + (-12) = -4. +9 comes from the 9 protons and -12 comes from the 12 electrons.
So, if 4 electrons are added, the net charge is -4.
the concentration when 0.065 moles of NaNO3 are dissolved in enough water to make 150 ml of solution is calculated as follows
concentration (molarity) = moles/volume x1000
molarity is therefore= 0.065moles/ 150 x1000 = 0.43M
Well if it loses one electron, then you would have more protons, so I would assume you would have a positive charge :)
Mass of methane takne = 1.5g
moles of methane used = masss / molar mass = 1.5 / 16 = 0.094 moles
mass of water = 1000 g
Initial temperature of water = 25 C
final temperature = 37 C
specific heat of water = 4.184 J /g C
1) Heat absorbed by water = q =m• C• ΔT = 1000 X 4.184 x (37-25) = 50208 Joules
2) Heat absorbed by calorimeter = Heat capacity X ΔT = 695 X (37-25) = 8340 J
3) Total heat of combustion = heat absorbed by water + calorimeter = 50208 + 8340 = 58548 Joules
This heat is released by 0.094 moles of methane
So heat released by one mole of methane =
- 622851.06 Joules = 622.85 kJ / mole
4) standard enthalpy of combustion = -882 kJ / mole
Error = (882-622.85) X 100 / 882 = 24.84 %