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6.101 Laser welding is a technique in which a tightly focused laser beam is used to deposit enough energy to weld metal parts together. Because the entire process can be automated, it is commonly used in many large-scale industries, including the manufacture of automobiles. In order to achieve the desired weld quality, the steel parts being joined must absorb energy at a rate of about 104 W/mm2. (Recall that 1 W = 1 J/s.) A particular laser welding system employs a Nd:YAG laser operating at a wavelength of
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Chemistry for Engineering Students
- Of the five elements Sn, Si, Sb, O, Te, which has the most endothermic reaction? (E represents an atom.) What name is given to the energy for the reaction? E(g)E+(g)+earrow_forwardIn X-ray fluorescence spectroscopy, a material can be analyzed for its constituent elements by radiating the material with short-wavelength X rays, which induce the atoms to emit longer-wavelength X rays characteristic of those atoms. Tungsten, for example, emits characteristic X rays of wavelength 0.1476 nm. If an electron has an equivalent wavelength, what is its kinetic energy?arrow_forwardMicrowave ovens use microwave radiation to heat food. Theenergy of the microwaves is absorbed by water molecules infood and then transferred to other components of the food.(a) Suppose that the microwave radiation has a wavelengthof 11.2 cm. How many photons are required to heat 200 mL ofcoffee from 23 to 60 °C? (b) Suppose the microwave’s power is900 W 11 watt = 1 joule@second2. How long would you haveto heat the coffee in part (a)?arrow_forward
- Use the energy at this (more energetic) wavelength to calculate the number of calories a plant could make if it were perfectly efficient and absorbed 1 mole of photons at this wavelength. (1 calorie = 4.184 Joules, 1 Calorie = 4.184 KJ).arrow_forward(a) Calculate the energy in joules of a 3.23 g object moving at a speed of 713 m/s.Ek = J(b) Determine how much greater the electrostatic energy is between charges of +2 and −2 than it is between charges of +1 and −1 (assume that the distance between the charges is the same in each case).1.5 times2.0 times2.5 times3.0 times3.5 times4.0 times4.5 times5.0 timesarrow_forwardFrom Einstein’s most famous equation, how much energy in British therrmal unit (btu) can theoretically be released from 38 moles of hydrogen gas? [1 btu=1055.056 joules], [1 Joule = 1kg m²/s²]arrow_forward
- Consider light with a wavelength of 5.41 × 10⁻¹⁰ m. How much heat is required to heat 1 cup (237 g) of water from 25 °C to 100 °C? (s(H₂O) = 4.184 J/g・°C) How many photons would be required to heat 1 cup of water?arrow_forwardCalculate the change in energy for the following processes: Na(g) + Cl(g) → Na^+1(g) + Cl^-1(g) Ca(g) + 2Br(g) → Ca^+2(g) + 2Br-1(g)arrow_forwardA microwave oven generates photons at a frequency of 900 GHz. Assuming all the photonenergy is absorbed by water, how many photons would it take to heat 125 g of water from 25˚C to 100˚C?arrow_forward
- Calculate the change in energy for an electron transitioning from the n=6 state to n=3 state. Give your answer in attojoules.arrow_forwardCalculate the change in energy for an electron transitioning from the n=5 state to the n=2 state. Give your answer in attojoules. Please be sure to include the correct sign.arrow_forward1. 2. Match the thermochemistry terms to their proper definitionarrow_forward
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