chem exam 2

7.Which of the following salts will dissolve in water? A) CaSO4 B) AgCl C) Na3PO4 D) Na2CO3 E) PbF2

E

Atomic emission- an electron transmission of an Hydrogen atom in the Bahlmer series (final state =2) produces light with a wavelength of 486.135 nm. what's the initial energy state?

E= hc / lamba E= -2.18x10^18( z^2/ nf^2 - z^2/ ni^2 ) ni=4

Photoelectric effect and de Broglie Wavelength - lead foil has a work function of 4.14 ev. given 1 ev= 1.6022 x10^-19. a) what will be the velocity in m/s of the departing from this lead surface if you use 266 nm light?

Ke= Ephoton - IO = Ephoton = hc/ lamba ( wavelength) KE= 1/2 m^2 > v = square root 2Ke/m

8. 2.0 M Mg(NO3)2 (aq) is mixed with 2.0 M NaF (aq). Will a precipitate form upon the mixing of these two solutions? If a precipitate does form, what is its chemical formula?

MgF2

From the following list of observations, choose the one that most clearly supports the conclusion that photons have particle characteristics.

photoelectric effect

A26gsampleofaluminumat100°Cisaddedto100gofwaterat22°Cinaconstant pressure calorimeter. The specific heat capacity of aluminum is 0.903 J/g°C and the specific heat capacity of water is 4.18 J/g°C. What is the final temperature of the water in °C?

q aluminum = -qwater m aluminum s aluminum delta T = -m water s water Delta T

Which form of electromagnetic radiation has the greatest frequency?

gamma rays have highest frequencies

Photoelectron effect part b) given that the mass of an electron is 9.109x10^-31 Kg, what is the de Broglie effect wavelength of this departing electron?

lamba = h/p = h/mv mx 10^9= nm/ 1 m

Would an electron confined to the sphere of a hydrogen atom have a larger or smaller range of momentums than one confined to the sphere of a uranium atom?

larger

If 65 mL of a 1.8 M solution of Cu(NO3)2 solution is diluted to a final volume of 450 mL by adding water, what is the molarity of the diluted solution?

m1x v1= m2x v2

.Iron is obtained from iron ore by reduction with carbon monoxide as follows: 𝐹𝑒2𝑂2(𝑠) + 3𝐶𝑂(𝑔) → 2𝐹𝑒(𝑠) + 3𝐶𝑂2(𝑔) Formula Fe (s) Fe2O3 (s) CO (g) CO2 (g) O (g) ∆𝑯°𝒇 (𝒌𝑱/𝒎𝒐𝒍) 0.0+ 824.2 -110.5 -393.5 +249.2 O2 (g) 0.0 calculate enthalpy

= standard enthalpy of reaction= entity B= stoichiometric number= standard enthalpy of formation ΔH=ΔU+PΔV

What is the ionization energy of the hydrogen-like He?

Bohr's model is used to solve this question, According to this E=−13.6×n2Z2​ So, in this the E is equal to energy of electron in nth shell of atom whose atomic number is Z . Now, same amount of energy with opposite sign must be given to electron in order to remove it. I.E.=−13.6×Z2eV (As n=1) Since for Lithium, Z=3 Therefore, you get I.E.=−122.4eV

Consider an atom traveling at 1% of the speed of light. The de Broglie wavelength is found to be 3.31 × 10-15 m. Which element is this? Hint: 1J = 1kgm2/s2 and molar masses are reported in g/mol (so yes, you need Avogadro's number)

Ca

electromagnetic radiation - Dr. Ray's green laser pointer has a wavelength of 532 nm. What's frequency, in Hz, of this light?

c= wavelength x velocity> v= c ( speed of light (2.998x10^8) / wavelength (lambda)

the following is an acid- base neutralization equation HCl ( aq ) + AgNo3 > HNO3 (aq) + AgCl (s)

false

Insoluble

sulfides (s2) - Ca2+, Ba2+, Sr2+, Mg2+, Na+, K+, and NH4+ Hydroxides - except Alkali metals (Group I) and ammoniumNa+, K+, etc.Al3+, NH4+ Carbonates, oxalates, chromates, and phosphatesCO32-, C2O42-, CrO42-, and PO43- except Alkali metals (Group I) and ammoniumNa+, K+, etc.NH4+*Lithium phosphate is poorly soluble

electrons have wave problems

true