28. \( \mathrm{HgO} \rightarrow \mathrm{Hg}+\mathrm{O}_{2} \)

A partir de la siguiente ecuación de combustión de octano, si reaccionan 59.2 gramos de octano, ¿Cuántos gramos de Oxígeno se necesitan? \[ \mathrm{C}_{8} \mathrm{H}_{18}+25 / 2 \mathrm{O}_{2}-\cdots>8 \mathrm{CO}_{2}+9 \mathrm{H}_{2} \mathrm{O} \] Considera: \( \mathrm{C}: 12, \mathrm{O}: 16, \mathrm{H}: 1 \)

A formula connecting density \( (d) \), mass \( (m) \) and volume \( (v) \) is \[ d=\frac{m}{v} \] \( m=30.14 \mathrm{~g} \) after being truncated to 2 d.p. \( v=3.78 \mathrm{~cm}^{3} \) after being truncated to 2 d.p. Calculate the lower and upper bounds of \( d \). Round your answers to \( 2 \mathrm{~d} . \mathrm{p} \).

При образовании 2,2г СО \( { }_{2} \) по уравнению реакции: \( \mathrm{C}(\mathrm{тв})+\mathrm{O}_{2}=\mathrm{CO}_{2}(\mathrm{r}) \) выделилось 19,7 кДж теплоты. Стандартная энтальпия образования \( \mathrm{CO}_{2}(\mathrm{r}) \) в кДж/ моль равна -197 +394 +197 \( -394 \times \)

A chemist carefully measures the amount of heat needed to raise the temperature of a 0.58 kg sample of a pure substance from \( 57.4^{\circ} \mathrm{C} \) to \( 67.4^{\circ} \mathrm{C} \). The experiment shows that \( 27 . \mathrm{kJ} \) of heat are needed. What can the chemist report for the specific heat capacity of the substance? Be sure your answer has the correct number of significant digits.

A partir de la siguiente ecuación de combustión de octano, si reaccionan 59.2 gramos de octano, ¿Cuántos gramos de Oxígeno se necesitan? \[ \mathrm{C}_{8} \mathrm{H}_{18}+25 / 2 \mathrm{O}_{2}-->8 \mathrm{CO}_{2}+9 \mathrm{H}_{2} \mathrm{O} \] Considera: \( \mathrm{C}: 12, \mathrm{O}: 16, \mathrm{H}: 1 \)