Ca + Cr2O7{-2} = Ca{2+} + Cr{+3}
Blance the redox please someone help me I got exam tomorrow and I got to go sleep soon
Ca + Cr2O7{-2} = Ca{2+} + Cr{+3}
Ca is zero on left to 2+ on right. delta electron = 2 lost.
Put a 2 in fron of Cr^3+ so we can compare apples with apples.
Ca + Cr2O7{-2} = Ca{2+} + 2Cr{+3}
Now 2 Cr on left are 12+; on right 2Cr^3+ = 6+ so that's a gain of 6 electrons.
Multiply Ca part by 3 and Cr2O7^2- by 1 to get this
3Ca + Cr2O7{-2} = 3Ca{2+} + 2Cr{+3}
Now add 7H2O to balance O, then 14H^+ on left t balance the H.
3Ca + Cr2O7{-2} + 14H^+ = 3Ca{2+} + 2Cr{+3} + 7H2O
3 Ca on left and right.
2 Cr on left and right
7 O on left and right
14 H on left and right.
12+ charge on left; 12+ on right.
:-).
Any questions.
In acidic aqueous solution you use water to balance oxygen and hydrogen cations to balance hydrogen.
Ca = Ca{2+} + 2 ē
Cr2O7{2-} + 14 H{+} + 6 ē = 2 Cr{3+} + 7 H2O
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3 Ca + Cr2O7{2-} + 14 H{+} = 3 Ca{2+} + 2 Cr{3+} + 7 H2O
Ca = Ca2+ + 2 e-
Cr2O72- + 14 H+ + 6 e- = 2 Cr3+ + 7 H2O
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2 Ca = Ca2+ + Cr2O72- + 14 H+ = 2 Ca2+ + 2 Cr3+ + 7 H2O
Opps. Cut and paste error.
2 Ca + Cr2O72- + 14 H+ = 2 Ca2+ + 2 Cr3+ + 7 H2O
To balance the given redox equation: Ca + Cr2O7{-2} = Ca{2+} + Cr{+3}, you can follow these steps:
Step 1: Determine the oxidation states of each element in the equation.
Looking at the equation, we can see that the oxidation state of Ca changes from 0 to +2, and the oxidation state of Cr changes from +6 to +3. Note that the oxidation state of oxygen is always -2.
Step 2: Identify the elements that are being oxidized and reduced.
In this equation, Ca is being oxidized (its oxidation state is increasing), and Cr is being reduced (its oxidation state is decreasing).
Step 3: Balance the atoms other than oxygen and hydrogen.
Count the number of each type of atom on both sides of the equation. We have:
Ca: 1 on the left side, 1 on the right side
Cr: 2 on the left side, 1 on the right side
O: 7 on the left side (as part of Cr2O7{-2}), 2 on the right side
So, to balance the atoms, we need to put a coefficient of 2 in front of Ca on the right side, and a coefficient of 7 in front of Ca2O7{-2} on the left side.
The updated equation becomes:
2Ca + Cr2O7{-2} = 2Ca{2+} + Cr{+3}
Step 4: Balance the oxygen atoms by adding water (H2O) to the side that needs more oxygen.
In this case, there are 7 oxygen atoms on the left side, and only 2 on the right side. To balance the equation, you need to add 5 water molecules to the right side.
The updated equation becomes:
2Ca + Cr2O7{-2} + 5H2O = 2Ca{2+} + Cr{+3}
Step 5: Balance the hydrogen atoms by adding H+ ions to the side that needs more hydrogen.
In this case, there are 10 hydrogen atoms on the right side (5 water molecules), and none on the left side. So, to balance the equation, you need to add 10 H+ ions to the left side.
The final balanced equation becomes:
2Ca + Cr2O7{-2} + 5H2O + 10H+ = 2Ca{2+} + Cr{+3} + 10H+
Now, the equation is balanced in terms of atoms and charge. However, if you are required to write the equation in a basic solution (with OH- ions), you may need to add additional steps to neutralize the excess H+ ions.