Question

General Chemistry

Two masses m1 =2.0 kg and m2 =4.0 kg are attached to each other via a red cord that runs over a pulley as shown in the diagram below. Mass m2 is allowed to fall to the ground from h = 1.0 m as shown in the diagram. Assume both the pulley and surface of the incline are frictionless and both the string and pulley are massless and answer the following questions in SI units to the correct number of significant figures:

a) as mass m, falls what is the acceleration of the two masses?

b) calculate the velocity of the masses just before mass m2 hits the ground using the law of conservation of energy AK + AU = 0 where AK is the change in the kinetic energy, and AU is the change in the potential energy, of the two masses.

Verified

### Question 45009

General Chemistry

15.9 g of CaCO3 decomposed and 7.31 g of CaO are obtained what is the percent yield of CaO obtained
\mathrm{CaCO3}(\mathrm{s}) \rightarrow \mathrm{CaO}(\mathrm{s})+\mathrm{CO} 2(\mathrm{~g})

### Question 45008

General Chemistry

(20). After completing a titration, you determined 0.52 mol of sodium hydroxide were required to reach the endpoint of sulfuric acid sample of unknown concentration. Your acid sample was 45 mL. What is the concentration of your acid? (Hint: is the reaction balanced?)
\mathrm{H} 2 \mathrm{SO} 4(\mathrm{aq})+\mathrm{NaOH}(\mathrm{aq}) \rightarrow \mathrm{Na2SO4}(\mathrm{aq})+\mathrm{H} 2 \mathrm{O}(1)

### Question 45007

General Chemistry

(18). Find the mass of a metal object (in grams) that was heated to 105°C and placed in 27 g of water at 13°C The final temperature of the water is 40°C. The C water = 4.184 J/g°C and C metal = 0.184 J/g°C.

### Question 45006

General Chemistry

(17). Determine the molarity of a solution formed by dissolving 48.9 g LiBr in enough water to yield a total solution volume of 750.0 mL.

### Question 45005

General Chemistry

(12). A metal cube has an edge length of 2.44 cm and a mass of 16.28 g. Calculate the density of the metal.

### Question 44215

General Chemistry

A lab technician had a sample of radioactive Americium. He knew it was one of the isotopeslisted in the table below but did not know which one. The sample originally contained 0.008g of the isotope, but 120 minutes later it contained 0.004 g. Use this information to answerthe following questions. (3 points)
A. How many half-lives have passed?
B. What is the half-life of the sample?
C. Which isotope did he have? (

### Question 44214

General Chemistry

A. Name three kinds of radioactive decay and provide the symbol for each that is used to represent the product given off. (3 points)
\text { i. } a \text { - decay (1 point) }
\text { iii. Y - decay (1 point) }
\text { ii. } \beta \text { - decay (1 point) }
{ }_{1}^{2} \mathrm{H}+{ }_{1}^{2} \mathrm{H} \rightarrow \frac{3}{2} \mathrm{He}+{ }_{0}^{1} \mathrm{n}

### Question 44213

General Chemistry

A. What two competing fundamental forces are at work inside the nucleus of an atom? (1point)
B. How can the ratio of number of protons to neutrons in the nucleus be used to predict thestability of a nucleus? (2 points)
C. How much energy would be released if 0.00023 kg of plutoniumthrough radioactive decay? (2 points)were converted to energy

### Question 44212

General Chemistry

Use the emission spectra shown to answer the following questions (note the direction of thewavelength scale):
A. A high school student acquired an emission spectrum of an unknown sample. He knewthe unknown sample contained one of the elements, whose spectra are shown above. Theemission spectrum of his sample showed a strong emission at 610 nm but not at 480 nm.Which element did his unknown sample contain? (2 points)
B. Element A above has a strong emission around 670 nm. Does this emission line representa lower energy or higher energy transition than the emission line at 428 nm? Explain youranswer. (2 points)
C. Why does each element have its own unique emission spectrum? (2 points)

### Question 44211

General Chemistry

A. Write a set of four possible quantum numbers for the circled electron. (There could bemore than one correct answer.) (4 points)
n =| =m, =II
B. The electron in a hydrogen atom can undergo a transition from n = 6 to n = 1, emitting aphoton with energy 2.11 x 10-18 J. (2 points)
i. What is the frequency of this transition? (1 point)
ii. How does this transition show that the energy of a photon is quantized? (1 point)
C. Why is it impossible for an electron to have the quantum numbers n = 3, | = 0, m, = 1, m, =
+\frac{1}{2} ?(2 \text { points })