A flask contains a gaseous mixture of 3.01mol of hydrogen and 5.84mol of oxygen gases. When these gases react, steam is produced.

a) Balance the equation for this reaction. H2(g) + O2(g) H2O(g)

b) What is the limiting reagent?
c) How many grams of steam are produced?
d) How many moles of limiting reagent remain unreacted? e) How many moles of excess reagent remain unreacted?

A flask with a sample of gas at room temperature and pressure weighs 97.4842 g. The same flask with air (density = 1.17 g/L) weighs 96.8848 g. The same flask filled with water (d = 0.998 g/mL) weighs 345.86 g. The pressure in the room is 0.989 atm and the temperature is 22.2 °C.

1. Calculate the volume of the flask.

2. Calculate the mass of the air that the flask can hold.

3. Calculate the mass of the empty (no air) flask.

4. Calculate the mass of the gas in the flask.

5. Use the Ideal gas law to calculate the moles of gas in the flask.

6. Calculate the molar mass of the gas in the flask.

4. Calculate the pH of the following salt solutions (5 pts each). a. 0.237 M sodium cyanide, NaCN (aq) (HCN ka = 4.0 x 10-10) b. 0.166 M ammonium iodide, NH4I (aq) (NH4+ ka = 5.6 x 10-10)

Molecular Orbital Theory

1.1 Which model, the Lewis electron dot structure or the MO energy level diagram, better describes the bonding in O₂? Remember that liquid O₂ is attracted into the magnetic field of a large magnet.

True or False.

_____ MO theory allows us to avoid the use of resonance.

_____ Resonance is a concept which arises from the limitations of Lewis electron dot structures

1.2 As we go from Li₂ to Li₃ to Li₄ to Li_n, the number of molecular orbitals formed from the 2s atomic orbitals goes from 2 to __ to __ to __ respectively, and the spacing between energy levels _________.

1.3 In the case of a metal, the lowest unoccupied MO is only infinitesimally higher in energy than the highest occupied MO, so it takes very little energy to cause electrons to move in a metal wire. In the case of a semiconductor, there is a _____ band gap between the full valence band and the empty conduction band. In the case of an insulator, there is a _____ band gap between the full valence band and the empty conduction band.

Explain these facts: (a) Copper and iron have several oxidation states, whereas zinc exists in only one.

(b) Copper and iron form colored ions, whereas zinc does not.

(c)Hydrated Mn2+ ions are practically colorless even though they possess five 3d electrons.

find the ratio effusion rates of hydrogen gas and krytpon gas.

Using only the elements Ca, Cl, Si, give formulas for the following: (a) an ionic compound. (b) a molecular compound with polar covalent bonds that obeys the octect rule and has no formal charge. For part b I drew the lewis structure Cl(double bond)-Ca-(double bond)Cl with two lone pair on each chloride, is that correct? Please explain. Thank you.

what is the difference between absorption and emission? transmission and reflection?

when plotting a graph of A vs B, what does it mean if one says that A is directly proportional to B? what would the graph look like?

what are the four steps of the scientific method?

You used 50.0mL of hydrochloric acid with 0.500g of magnesium. If the temperature changed from 20.0oC to 24.0oC, what was the heat of reaction (ΔH) for your experiment? Report your answer in kJ without writing the units.

QUESTION 1

Of the quantum numbers n, l, m_l, and m_s, which is the spin quantum number?

1 points   

QUESTION 2

Valence electrons are the outer electrons of an atom.

True

False

1 points   

QUESTION 3

What type of bond is between the two carbon atoms in the molecule ethane (C₂H₆)?

1 points   

QUESTION 4

A molecule has a carbon atom that is best described by sp³ hybridization. Which bond angles (in degrees) come closest to describing the carbon?

1 points   

QUESTION 5

Atoms that obey the octet rule have how many valence electrons?

1 points   

QUESTION 6

A molecule has a carbon atom that is best described by sp hybridization. How many other atoms are connected to this carbon?

1 points   

QUESTION 7

The electron configuration, 1s²2s²2p⁶ is correct for which of the following atoms.

1 points   

QUESTION 8

Choose the answer that best completes the sentence: In molecular orbital theory, a single bond consists of ______.

1 points   

QUESTION 9

The compound N₂ contains only this kind of bond.

1 points   

QUESTION 10

What is the maximum number of electrons that can be contained in the 4s orbitals?

What is the bonding functional group and elution order of the following: propyl acetate, butyl acetate, methanol, ethanol, 2-butanone, and 4-methyl-2-pentatnone

Diazomethane is a highly poisonous, explosive compound because it readily evolves N₂. Diazomethane has the following composition by mass: 28.57% C; 4.80% H; and 66.64% N. The molar mass of diazomethane is 42.04 g/mol. Find the molecular formula of diazomethane, draw its Lewis structure, and assign formal charges to each atom. Why is diazomethane not very stable? Explain.

Consider the titration of 70.0 mL of 0.0300 M (CH3)3N (a weak base; Kb = 6.40e-05) with 0.100 M HBr. Calculate the pH after the following volumes of titrant have been added:

(a) 0.0 mL

pH = _____

(b) 5.3 mL

pH = _____

(c) 10.5 mL

pH = _____

(d) 15.8 mL

pH = _____

(e) 21.0 mL

pH = _____

(f) 27.3 mL

pH = _____

Calculate the mass in grams of hydrogen chloride produced when 5.95 L of molecular hydrogen measured at STP reacts with an excess of molecular chlorine gas.

H2(g) + Cl2(g) → 2HCl(g)