1. A 100-watt lightbulb radiates energy at a rate of 100 J/s (The watt, a unit of power, or energy over time, is defined as 1 J/s). If all of the light emitted has a wavelength of 505nm, how many photons are emitted per second? (Assume three significant figures in this calculation.)

2.Calculate the de Broglie wavelength of a 143-g baseball traveling at 80 mph .

3.An electron undergoes a transition from an initial (ni) to a final (nf ) energy state. The energies of the ni and nf energy states are −2.179×10⁻¹⁸ J and −8.720×10−20 J, respectively.

Calculate the wavelength (λ) of the light in nanometers (nm) corresponding to the energy change (ΔE) value of this transition. You can use the following values for your calculations:

Planck′s constant (h)speed of light (c)1 m===6.626×10−34 J⋅s2.998×108 m/s109 nm

What are some of the problems associated with mining phosphate rock? I've read toxic elements like cadmium and I believe uranium and selenium are found in phosphate rock deposits, but would like for somebody to confirm this with a credible source I can use in a paper. Also are these toxic elements also found in superphoshpate fertilizers? I am trying to understand the impact phosphate mining and phosphate fertilizers have on the soil and appreciate any sources and/or information relevant to the topic. Thank you    

A mixture containing 2.91 g each of CH₄(g), C₂H₄(g) and C₄H₁₀(g) is contained in a 1.50 L flask at a temperature of 35°C.

(a) Calculate the partial pressure of each of the gases in the mixture.

(b) Calculate the total pressure of the mixture.
___ atm

What was the initial concentration of 100ml of KBr solution, if after adding water to dilute it, 300ml of a 4 percent solution was obtained?

Consider the titration of 65 mL of 1.75 M diethylamine, (CH3CH2)2NH (Kb = 1.3×10-3) with 0.25 M HCl. How many mL of HCl will need to be added to the diethylamine solution to reach a pH of 11.11?

2. Phosphoric acid (H3PO4) is a triprotic acid with the following pKa values: pKa1 = 2.15 pKa2 = 7.20 pKa3 = 12.35

a). You wish to prepare a 1.000 L of a 0.0450 M phosphate buffer at pH 6.8. Which of the following salts do you use (PICK 2) and what mass of each salt will you add to the mixture? H3PO4 (M.W.= 97.995) KH2PO4 (M.W.=136.086) Na2HPO4 (M.W.=141.959) AlPO4 (M.W.=121.953) 2

b). A concentrated phosphate buffer known as “phosphate buffered saline” (or PBS) is made with the salts you choose from above in addition to NaCl and KCl. The 10x concentrated solution has a pH ~6.8 and the 1x concentrated (i.e., diluted with water) solution is ~7.1. Why?

c). You accidently grabbed the 10x concentrated phosphate buffered saline (or 10xPBS) instead of the 1xPBS solution and start to adjust the pH of your buffer with NaOH to reach your desired buffer pH. You notice it is taking much more base than with your usual 1xPBS buffer. Why?

Compound X, C₈H₁₇Cl, is a chiral product of the radical chlorination of 4-methylheptane.
X reacts in S_N2 fashion with NaI in acetone to form Z, C₈H₁₇I. When the reactant is the R-enantiomer of X, only the R-enantiomer of Z is formed.
Draw a structural formula for X; do not show stereochemistry.

I don't even know how to go about this, I have been trying to do these types of problems for a while now and can't seem to get one right

Using the mechanism of hydroboration-oxidation as an example, explain what is meant by reterntion of configuration.

Potassium dichromate (K2Cr2O7) is a bright orange salt that can be converted to a blue-violet solution of Cr3+ ions. Under certain conditions, K2Cr2O7 reacts with ethanol (C2H5OH) to produce carbon dioxide gas. The legal definition of intoxication is a blood alcohol (C2H5OH) level of 0.08% by mass or higher. In a given case, 35.48 mL of 0.05182 M K2Cr2O7 was required to titrate a 50.02 g sample of blood. From the tested sample, should the person be arrested for a DUI?

Assume that only the ethanol reacts with the potassium dichromate.

C₂+H₅+OH (l) + K₂Cr₂O₇ (aq) ----> CO₂ (g) + K⁺+ Cr³⁺

Suppose the 0.1 M Zn 2+ solution has been diluted (instead of the Cu 2+ solution), would the measured cell potentials have increased or decreased? Explain why the change occurred.

access important values if needed for this question.

A piece of solid lead weighing 38.4 g at a temperature of 315 °C is placed in 384 g of liquid lead at a temperature of 372 °C. After a while, the solid melts and a completely liquid sample remains. Calculate the temperature after thermal equilibrium is reached, assuming no heat loss to the surroundings.

The enthalpy of fusion of solid lead is ΔH_fus = 4.77 kJ/mol at its melting point of 328 °C, and the molar heat capacities for solid and liquid lead are C_solid = 26.9 J/mol K and C_liquid = 28.6J/mol K.

T_final =  °C

1. If the boiling point of (R,R)-1,2-diaminocyclohexane is 110°C, what do you think the boiling point of (S,S)-1,2-diaminocyclohexane is?

2. Based on measured roations, how can one predict how well one separated 1,2-diaminocyclohexane enantiomers? Please explain the answer and how results could be improved (how you can better separate the two enantiomers)

thankyou