1. A student attempts to identify an unknown compound by the method used in this experiment. She finds that when she heated a sample weighing 0.5015 g the mass went down appreciably, to 0.3432 g. When the product was converted to a chloride, the mass went up, to 0.3726 g.

a. Is the sample a carbonate? ____________ Give your reasoning.

b. What are the two compounds that might be in the unknown? ____________ and ____________

c. Write the chemical equation for the overall reaction that would occur when the original compound was converted to a chloride. If the compound is a hydrogen carbonate, use the sum of Reactions 1 and 2. If the sample is a carbonate, use Reaction 2.

Write the equation for a sodium salt and then for a potassium salt.

d. How many moles of the chloride salt would be produced from one mole of original compound? ____________

e. How many grams of the chloride salt would be produced from one molar mass of original compound? Molar masses: NaHCO3 ____________ g Na2CO3 ____________ g NaCl ____________ g KHCO3 ____________ g K2CO3 ____________ g KCl ____________ g If a sodium salt, ____________ g original compound → ____________ g chloride If a potassium salt, ____________ g original compound → ____________ g chloride

f. What is the theoretical value of Q, if she has an Na salt? ____________ if she has a K salt? ____________ g.

What was the observed value of Q? ____________

h. Which compound did she have as an unknown?

What mass of water (in grams) forms from the reaction of 2.22 L of hydrogen gas and 2.24 L of oxygen gas? Both gases are at 726 torr and 7.8 ^oC.

For cyclohexane, C6H12, the normal melting point is 6.47°C and the heat of fusion at this temperature is 31.3 J/g. Find the freezing point of a solution of 110 mg of pentane, C5H12, in 16.45 g of cyclohexane. Assume an ideally dilute solution and that only pure cyclohexane freezes out.

A sample of an ideal gas has a volume of 3.65 L at 13.00 °C and 1.80 atm. What is the volume of the gas at 24.00 °C and 0.990 atm?

Given the half-cells:

Ni/Ni2+ and Fe/Fe2+

a) Chose the anode and cathode. b)Calculate Eo and DG for this reaction. c) Calculate what the new cell potential (E) would be if the non equilibrium concentrations were [Ni2+] =.40 M and [Fe2+] = 0.30 M. Calculate the how long you would have to run the battery at 6 amps to make this battery die at zero volts.

Put the terms in the appropriate blanks.

What is the difference between a 10% (v/v) methanol (CH₃OH) solution and a 10% (m/m) methanol solution?

A 10% (v/v) methanol solution can be made by adding _________ of methanol to _________ of water, while a 10% (m/m) methanol solution can be made by adding _________ of methanol _________ of water.

a. 10 mL

b. 90 mL

c. 90 g

d. 100 g

e. 100 mL

f. 10 g

How do temperature and pressure affect the solubility of solids and gases in water?

An increase in temperature usually __________ the solubility of solids and ________ the solubility of gases in water. An increase in pressure of a gas above a liquid _________ the solubility of a gas within that solution and _________ the solubility of solids.

a. increases

b. decreases

c. has no effect on

Describe the formation of an aqueous LiBr solution, when solid LiBr dissolves in water.

The _________ at the surface of the solid are pulled into solution by the _________ water molecules, where the ________ process surrounds

1. Which chemical is formed upon the addition of HCl to methyl orange? Name (not IUPAC) and draw it.

2. Which chemical is formed upon the addition of NaOH to methyl orange? Name (not IUPAC) and draw it. Explain how you know.

3. Which chemical is formed upon the addition of HCl to phenolphthalein? Name (not IUPAC) and draw it.

4. Which chemical is formed upon the addition of NaOH to phenolphthalein? Name (not IUPAC) and draw it. Explain how you know.

What are the mole fraction (X) and molality (m) of ethanol (C₂H₅OH) in an aqueous solution that is 45.0% ethanol by volume? The density of water is 1.00 g/mL and that of ethanol is 0.789 g/mL.

mole fraction = ?????;

molality =

??? m

1. A galvanic cell is based on the following half-reactions at 285 K:

Ag⁺ + e^- → Ag     E^o = 0.803 V  
H₂O₂ (aq) + 2 H⁺ + 2 e^- → 2 H₂O     E^o = 1.78 V

What will the potential of this cell be when [Ag⁺] = 0.571 M, [H⁺] = 0.00341 M, and [H₂O₂] = 0.895 M?

Please show full work .

How much heat (in kJkJ) is required to warm 13.0 gg of ice, initially at -14.0 ∘C∘C, to steam at 108.0 ∘C∘C? The heat capacity of ice is 2.09 J/g⋅∘CJ/g⋅∘C and that of steam is 2.01 J/g⋅∘CJ/g⋅∘C.

74) Epoxy is a(n) ?

a) elastomer

b) thermoset

c) thermoplastic

d) composite

.

75) In tempering of steel, temperature treatments around 400 °C are used to?

a) reduce brittleness and increase ductility (toughen) by transforming martensite morphology

b) increase strength and hardness by locking in martensite structure

c) increase strength and hardness by causing lower density glass layer to form on surface

d) reduce brittleness and increase ductility (toughen) by causing martensite morphology to form

.

76) Surface carburizing of steel involves

a) burning excess carbon out of the iron carbon alloy to form steel.

b) introducing extra carbon into surface of austenite to harden and toughen surface with quenching and formation of martensite.

c) forming martensite on the surface through rapid cooling to harden and toughen surface with quenching.

d) introducing extra carbon into surface of cementite to harden and toughen surface with quenching.

Please answer all of them without guessing!!! Thanks

Use data from Appendix IIB in the textbook to calculate the equilibrium constants at 25?C for each of the following reactions.

2NO(g)+O2(g)?2NO2(g) .

Express your answer using two significant figures.

With the aid of a clearly labelled schematic diagram, illustrate the main layout of a flame atomic absorption spectrometer with continuum source background correction. Describe briefly the purpose of each component.

Your diagram should include reference to the following components:

The hollow cathode lamp                           The flame and burner

The deuterium lamp                                   The monochromator

The modulator or chopper                          The detector

What is the effect of the following on the volume of 1 mol of an ideal gas?

(a) The pressure from 760 torr to 202 kPa, and the temperature changes from 37C to 155k.

(b) The temperature changes from 305K to 32C, and the pressure changes from 2 atm to 101k Pa.

(c) The pressure is reduced by a factor of 4 ( at constant T).