Chemistry Questions & Answers

If solutions of KCl and \( \mathrm{AgNO}_{3} \) are mixed, you should expect to see [p] precipitate. Type the formula of the expected precipitate in the space provided. You can't use subscripts for these types of answers, so type the subscripts as full-sized numbers. For example, \( \mathrm{H}_{2} \mathrm{O} \) would be typed as H 2 O . If no precipitate would be formed, type none in the answer space.

A sample of 500 g of radioactive lead-210 decays to polonium- 210 according to the function \( \mathrm{A}(\mathrm{t})= \) yr. (d) Find the half-life. (a) The amount of radioactive lead remaining after 4 yr will be \( \square \mathrm{g} \). (Round to the nearest integer as needed.) (b) The amount of radioactive lead remaining after 6 yr will be \( \square \mathrm{g} \). (Round to the nearest integer as needed.) (c) The amount of radioactive lead remaining after 10 yr will be \( \square \mathrm{g} \). (Round to the nearest integer as needed.) (d) The half-life is about \( \square \mathrm{yr} \). (Round to two decimal places as needed.)

4244_01Z1) A sample of 500 g of radioactive lead-210 decays to polonium- 210 according to the function \( \mathrm{A}(\mathrm{t})=500 e^{-0.032} \) yr. (d) Find the half-life. (a) The amount of radioactive lead remaining after 4 yr will be 440 g . (Round to the nearest integer as needed.) (b) The amount of radioactive lead remaining after 6 yr will be (Round to the nearest integer as needed.)

que las ecuaciones segúr \( 2 \mathrm{Mg}+\mathrm{O}_{2}-{ }^{-}-2 \mathrm{MgO} \)

4. 925 ccc de una solución de KOH en agua contienen 66 g de la base. Halla la concentración molar de la solución. R. \( 1,27 \mathrm{M} \) 5. Calcula la molalidad de cada una de las soluciones siguientes: a. 15 g de \( \mathrm{H}_{2} \mathrm{CO}_{3} \) en 420 g de \( \mathrm{H}_{2} \mathrm{O} \); b. 36 g de \( \mathrm{NaCl}^{2} \) en 100 g de \( \mathrm{H}_{2} \mathrm{O} \). R. a. \( 0,57 \mathrm{~m} ; \) b. \( 6,15 \mathrm{~m} \).

A sample of 500 g of radioactive lead- 210 decays to polonium- 210 according to the yr. (d) Find the half-life. (a) The amount of radioactive lead remaining after 3 yr will be \( \square \mathrm{g} \). (Round to the nearest integer as needed.)

Which of the following is a correct molecular equation for the reaction of a metal and an acid? \( \begin{array}{l}\mathrm{Ni}(s)+\mathrm{H}_{2} \mathrm{SO}_{4}(a q) \rightarrow \mathrm{NiSO}_{4}(a q)+2 \mathrm{H}_{2} \mathrm{O}(g)+\mathrm{SO}_{2}(g) \\ \mathrm{K}(s)+2 \mathrm{HNO}_{3}(a q) \rightarrow \mathrm{KNO}_{3}(a q)+\mathrm{NO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(l) \\ \mathrm{Zn}(s)+2 \mathrm{H}^{+}(a q) \rightarrow \mathrm{Zn}^{2+}(a q)+\mathrm{H}_{2}(g) \\ \mathrm{Mg}(s)+2 \mathrm{HNO}_{3}(a q) \rightarrow \mathrm{Mg}\left(\mathrm{NO}_{3}\right)_{2}(a q)+\mathrm{H}_{2}(g)\end{array} \)

A solution has a hydroxide ion concentration of \( 1.0 \times 10^{-5} \mathrm{M} \). What is the pOH of the solution? 5.00 12.00 9.00 -1.00

The concentration of \( \mathrm{H}^{+} \)in a solution is \( 1 \times 10^{-2} \mathrm{M} \). What is the hydroxide ion concentration? \( 1 \times 10^{-7} \mathrm{M} \) \( 1 \times 10^{-10} \mathrm{M} \) \( 1 \times 10^{-16} \mathrm{M} \) \( 1 \times 10^{-12} \mathrm{M} \)

Nitrous acid, \( \mathrm{HNO}_{2} \), is a weak acid. What is the reaction of nitrous acid in water? \( \mathrm{HNO}_{2}(a q)+\mathrm{OH}^{-}(a q) \rightarrow \mathrm{H}_{2} \mathrm{O}(l)+\mathrm{NO}_{2}^{-}(a q) \) \( \mathrm{HNO}_{2}(a q)+\mathrm{H}_{3} \mathrm{O}^{+}(a q) \rightleftharpoons \mathrm{H}_{2} \mathrm{O}(l)+\mathrm{H}_{2} \mathrm{NO}_{2}^{+}(a q) \) \( \mathrm{HNO}_{2}(a q)+\mathrm{H}_{2} \mathrm{O}(l) \rightarrow \mathrm{H}_{3} \mathrm{O}^{+}(a q)+\mathrm{NO}_{2}^{-}(a q) \) \( \mathrm{HNO}_{2}(a q)+\mathrm{H}_{2} \mathrm{O}(l) \rightleftharpoons \mathrm{H}_{3} \mathrm{O}^{+}(a q)+\mathrm{NO}_{2}^{-}(a q) \)