In the following overall chemical reaction, aluminum displaces chromium from chromium(iii) oxide and forms aluminum oxide.
2 al(s) + cr2o3(s) → 2 cr(s) + al2o3(s); δh = ?
find the change in enthalpy for this reaction, using hess' law and the enthalpy changes for the reactions given below.
(1a) 4 al(s) + 3 o2(g) → 2 al2o3(s); δh = −3351.4 kj
(2a) 4 cr(s) + 3 o2(g) → 2 cr2o3(s); δh = −2279.4 kj

Draw the structure for 5-isopropyl-2-methyl-3-nonene

What mass of natural gas (ch4) must you burn to emit 276 kj of heat?

Calculate the estimated density of each ball. use the formula d = m/v where d is the density, m is the mass, and v is the volume. record your calculations in table a of your student guide. given that the density of water is 1.0 g/cm3, make a prediction about whether each ball will float in water. record your prediction in table a. what is the estimated density of the table tennis ball? record your answer to the nearest hundredth