General Chemistry Answers

A 7.547 g fuel which has heating value of 33kJ/kg is burned in calorimeter and initially at 25.00 degC. Upon triggering the temperature become 28.50 degC

What is the calorimeter constant in J/K?

A 7.457 g fuel which has heating value of 33kJ/kg is burned in calorimeter and initially at 25.00 degC. Upon triggering the temperature become 28.50 degC

What is the delta T of the calorimeter? in degC

A student weighs out a 18.6 g sample of cobalt(II) bromide, transfers it to a 500 mL volumetric flask, adds enough water to dissolve it and then adds water to the 500 mL tic mark.

What is the molarity of CoBr₂ in the resulting solution?

Next, you will learn how to make a stacked fraction using the math equation editor. Re-type the expression shown into the answer area using stacked fractions. Open the Hint panel to learn how to use the tool bar to make a stacked fraction.

𝑎

𝑏+𝑐+𝑑+𝑒

a

b

+

c

+

d

+

e

You will find that you will be graded correctly for using the slash (/) symbol and parentheses instead of a stacked fraction, but the point of this question is to encourage you to practice making a stacked fraction, which can be useful for displaying a complicated expression clearly.

The combustion of a sample of butane, C4H10 (lighter fluid), produced 3.75 moles of water. 2C4H10 + 13O2 -------> 8CO2 + 10H2O

A. How many moles of carbon dioxide formed?

B. How many grams of butane burned?

C. How much oxygen was used up in grams?

1. Phosphoric acid can be prepared from phosphorus triiodide according to the reaction:

    Pl₃ (s)  +  H₂O(l) -----------> H₃PO₄(aq) + HI(g)

If 150 g of PI₃ (MM = 411.7 g/mol) is added to 250 mL OF H2O (g/mol), d = 1.00 g/mL), Identify which will be limiting and excess reagents. (10pts) How many grams of H₃PO₄ (MM = 97.99 g/mol) will be produced theoretically?

A student added zinc metal to a copper (II) nitrate solution to obtain copper metal by a single displacement

reaction. From the known moles of copper (II) nitrate solution, she calculated the expected mass of copper as

6.7 g. When she weighed the copper on a balance, the mass was 5.7 g.

Calculate the de Broglie wavelength of the following.

(a) An electron moving at a speed of 1.08×103 m s-1.

(b) A proton moving at a speed of 1.08×103 m s-1.

(c) A baseball with a mass of 147 grams moving at a speed of 33.1 m s-1.

(a) Wavelength electron = 

 m

(b) Wavelength proton = 

 m

(c) Wavelength baseball = 

 m

Calculate the molarity of a 5.1% acetic acid solution, assuming the density of the solution is 1.00g/ml

The power output of a laser is measured by its wattage, the number of joules of energy it radiates per second (1 W = 1 J s-1). A 450.-mW argon laser produces a beam of blue light with a wavelength of 457.9 nm (4.579×10-7 m).

(a) Calculate the energy carried by each photon.

(b) Calculate the number of photons emitted by the laser per second.

(a)   J per photon

(b)  photons per second