a. In your own words, explain the physical meaning of enthalpy. Is the change in enthalpy for a reaction an extensive (mass-dependent) property? Explain your answer. b. Explain how the value of ΔH for a reaction change upon: i) multiplying the reaction by an integer factor. ii) reversing the reaction. iii) Why do these relationships hold? c. What is Hess’s law and why is it useful?
Read DetailsUse the following table to answer the problems focused on the determination of oxidation numbers. Rules Operational considerations 1 The oxidation number of an atom in an elemental substance is zero. 2 The oxidation number of a monatomic ion is equal to the ion’s charge. 3 Oxidation number for common elements H, O , and halogens:H: +1 when combined with nonmetals; −1 when combined with metals.O: −2 in most compounds; Sometimes −1 (so-called peroxides, O22−); Very rarely − ½ (so-called superoxides, O2−); Positive values when combined with F (values vary).Halogens: −1 for F always; −1 for other halogens except when combined with oxygen or other halogens (positive oxidation numbers in these cases, varying values). 4 The sum of the oxidation numbers for all atoms in a molecule or polyatomic ion equals the charge on the molecule or ion. Determine the oxidation state of N in NO3-
Read DetailsAn account is opened with an initial deposit of $9,500 and earns 3.7% interest compounded semi-annually. What would the account be worth in 20 years? (Round your answer to the nearest cent.) [blank1] Hint: For the following, recall the compound interest formula, , where A(t) is the future value, P is the initial investment, r is the annual interest rate, n is the number of times compounded in a year, t is time in years.
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