The energy change if 84.0 g of CaO react with excess water is 98KJ of heat is released.
calculation
heat = number of moles x delta H
delta H = - 65.2 Kj/mol
first find the number of moles of CaO reacted
moles = mass/molar mass
the molar mass of CaO = 40 + 16= 56 g/mol
mass = 84 g
moles therefore = 84 g/56 g/mol =1.5 moles
Heat is therefore = 1.5 moles x -65.2 = - 97.8 Kj = -98 Kj
since sign is negative the energy is released
Answer:
54 g
Explanation:
1 mole of water = H2O
mass of 1 mole of H2O= mass of h2 + mass of o
= 2× mass of h +mass of o
= 2×1+16 =18 g
1 mole of water = 18g
3moles of water = 18×3g= 54g
Answer:False
Explanation:co2 or carbon dioxide is a compound not an element, you can even check this on the periodic table
First convert grams to moles
using molar mass of butane that is 58.1 g
3.50g C4H10 x (1 mol
C4H10)/(58.1g C4H10) = 0.06024 mol C4H10 <span>
<span>Now convert moles to molecules by using Avogadro’s number
0.06024 mol C4H10 x (6.022x10^23 molecules C4H10)/(1 mol
C4H10) = 3.627x10^22 molecules C4H10
And there are 4 carbon atoms in 1 molecule of butane, so use
the following ratio:
3.627 x 10^22 molecules C4H10 x (4 atoms C)/(1 molecule
C4H10)
<span>= 1.45 x 10^23 atoms of carbon are present</span></span></span>
Answer:
magnesium= +2
aluminum= +3
phosphorous= -3
lithium= +1
fluorine= -1
Explanation:
As fluorine having seven valance electrons in its outer most shell with atomic number nine. And for completing its outer most shell it needs one more electron that is why it form ion of -1 value.
Now Aluminum has three electrons in its outer most shell with atomic number 13. So it need to lose these three electrons in order to be in stable state that is why it have ion in +3 state.
Same rule apply for other elements too.
