Answer:
38.83 % of CaCO3
61.17 % of MgCO3
Explanation:
where Moles of CaCO3 is equals to x and MgCO3 is y we have that...
CaCO3 molar mass = 100.09 g / mol = 100.09 x
MgCO3 molar mass = 84.31 g / mol = 84.31 y
decomposition reactions :
CaCO3 ---> CaO + CO2
MgCO3 ---> MgO + CO2
So we have that , Moles of CaO = Moles of CaCO3 = x
and Moles of MgO = Moles of MgCO3 = y
CaO molar mass = 56.08 g / mol
MgO molar mass = 40.30 g / mol
CaO = 56.08 x
MgO = 40.30 y
"If the weight of the combined oxides is equal to 51.00% of the initial sample weight,"
total mass of MgO and CaO = 51.00 % of Total Mass of MgCO3 and CaCO3
thus
56.08 x + 40.30 y = 0.51 ( 100.09 x + 84.31 y )
56.08 x + 40.30 y = 51.04 x + 42.99y
5.04 x = 2.7 y
y = 1.87 x
CaCO3 % in the sample
= 100.09 x × 100 / ( 100.09 x + 84.31 y )
= 10009 x / ( 100.09 x + 84.31 × 1.87 x )
= 10009 x / ( x ( 100.09 + 157.66 ) )
= 10009 / 257.75
= 38.83 %
MgCO3 % in the sample
= 100 - 38.83
= 61.17 %
Answer:
3C3H8O2 and 16H2SO4
Explanation:
C3H8O2(aq) + K2Cr2O7(aq) → C3H4O4(aq) + Cr2(SO4)3(aq)
In acidic reaction you need to separate the half-reactions knows.
C3H8O2(aq) → C3H4O4(aq)
Cr2O7(2-) → Cr(+3) (aq)
Balance elements other than O and H. Add H2O to balance oxygen, balance hydrogen by adding protons (H+) and Balance the charge of each equation with electrons
C3H8O2(aq) + 2H2O(l) → C3H4O4(aq) + 8H(+) + 8e(-)
Cr2O7(2-) + 14H(+) + 6e(-) → 2Cr(+3) + 7H2O (aq)
Scale the reactions so that the electrons are equal. If not look for a common multiple. In this case is 24, 8*3=6*4. So for each equation multiply for the correct multiple. Then
3C3H8O2(aq) + 6H2O(l) → 3C3H4O4(aq) + 24H(+) + 24e(-)
4Cr2O7(2-) + 56H(+) + 24e(-) → 8Cr(+3) + 28H2O (aq)
Add the reactions and cancel out common terms and group the ions in compounds if u can.
3C3H8O2(aq) + 32H(+) + 4Cr2O7(2-) → 3C3H4O4(aq) + 4Cr2(SO4)3(aq) + 22H2O (aq)
We are in acidic medium so the H(+) must be from H2SO4. So 32H(+) is 16H2SO4 in reactives. Add SO4(2-) in products and balance
16H2SO4 +3C3H8O2(aq) + 4Cr2O7(2-) → 3C3H4O4(aq) 4Cr2(SO4)3(aq) + 22H2O (aq) + 4SO4(2-)
Then
16H2SO4 +3C3H8O2(aq) + 4Cr2O7(2-) → 3C3H4O4(aq) 4Cr2(SO4)3(aq) + 22H2O (aq) + + 2K2SO4 (aq)
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