Multiple Choice
An unknown weak base has a concentration of 0.170 M and a pH of 9.42. What is the value of K_b for this base?
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6. Chemical Quantities & Aqueous Reactions
Calculate Oxidation Numbers
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What is the oxidation state of an individual carbon atom in CaCO_3?
A
+4
B
+2
C
−4
D
0
Verified step by step guidance1
Identify the overall charge of the compound CaCO_3, which is neutral (0 charge).
Assign the known oxidation states: calcium (Ca) is an alkaline earth metal and typically has an oxidation state of +2, and oxygen (O) in most compounds is usually -2.
Let the oxidation state of carbon (C) be x. Since there are three oxygen atoms, their total contribution to the charge is 3 × (-2) = -6.
Write the equation for the sum of oxidation states in the compound: +2 (from Ca) + x (from C) + (-6) (from O) = 0.
Solve the equation for x to find the oxidation state of carbon: x = 0 - 2 + 6.
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