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A red laser pointer emits light at a wavelength of 488 nm. If the laser emits 7.5 × 10–4 J of energy per second in the form of visible radiation, how many photons per second are emitted from the laser?

For a proton (mass = 1.673 × 10–27 kg) moving with a velocity of 2.83 × 104 m/s, what is the de Broglie wavelength of the proton (in pm)?

Calculate the energy in the form of heat (in kJ) required to convert 325 grams of liquid water at 20.0 °C to steam at 115 °C. Assume that no energy in the form of heat is transferred to the environment. (Heat of fusion = 333 J/g; heat of vaporization = 2256 J/g; specific heat capacities: liquid water = 4.184 J/g⋅K, steam = 1.92 J/g⋅K)

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