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What quantity, in moles, of hydrogen is consumed when 179.6 kJ of energy is evolved from the combustion of a mixture of H2(g) and O2(g)? H2(g) + O2(g)  →  H2O(l); ΔrH° = –285.8 kJ/mol-rxn

A 100 g sample of each of the following metals is heated from 35°C to 45°C. Which metal absorbs the lowest amount of heat energy? Metal Specific Heat Capacity copper 0.385 J/(g·°C) magnesium 1.02 J/(g·°C) mercury 0.138 J/(g·°C) silver 0.237 J/(g·°C) lead 0.129 J/(g·°C)

If 46.1 g of copper at 11.6 °C is placed in 85.0 g of water at 72.4 °C, what is the final temperature of the mixture? The specific heat capacities of copper and water are 0.385 J/g ⋅ K and 4.184 J/g ⋅ K, respectively.

What is the energy per mole of photons of light with a wavelength of 690.8 nm?

How many valence electrons are present in the Lewis formula for the chlorite ion, Cl2–?

When 66.0 g of an unknown metal at 28.5 °C is placed in 83.0 g H2O at 78.5 °C, the water temperature decreases to 75.9 °C. What is the specific heat capacity of the metal? The specific heat capacity of water is 4.184 J/g⋅K.

Which of the following statements is/are CORRECT?   1. If a reaction occurs at constant pressure, q = ΔH.   2. The change in energy for a system is defined as the sum of the energies transferred as heat and work (i.e., ΔU = q + w).   3. If a reaction occurs at constant volume, q = w

If a cordless phone operates at a frequency of 9.00 × 108 s–1, what is the wavelength of this radiation?

A light emitting diode (L.E.D.) emits photons with an energy of J. What is the energy per mole of photons emitted? ​

​A device emits light at 219.4  nm.  What is the frequency of this radiation?