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± Convert between Units of Concentration Chemists often use molarity M, in moles/liter, to measure the concentration of solutions. Molarity is a common unit of concentration because the volume of a liquid is very easy to measure. However, the drawback of using molarity is that volume is a temperature-dependent quantity. As temperature changes, density changes, which affects volume. Volume markings for most laboratory glassware are calibrated for room temperature, about 20∘C.Fortunately, there are several other ways of expressing concentration that do not involve volume and are therefore temperature independent. |
A 2.400×10−2M solution of NaCl in water is at 20.0∘C. The sample was created by dissolving a sample of NaCl in water and then bringing the volume up to 1.000 L. It was determined that the volume of water needed to do this was 999.4 mL . The density of water at 20.0∘C is 0.9982 g/mL. Part A Calculate the molality of the salt solution. Express your answer to four significant figures and include the appropriate units.
SubmitHintsMy AnswersGive UpReview Part Part B Calculate the mole fraction of salt in this solution. Express the mole fraction to four significant figures.
SubmitHintsMy AnswersGive UpReview Part Part C Calculate the concentration of the salt solution in percent by mass. Express your answer to four significant figures and include the appropriate units.
SubmitHintsMy AnswersGive UpReview Part Part D Calculate the concentration of the salt solution in parts per million. Express your answer as an integer to four significant figures and include the appropriate units.
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In: Chemistry
Use Charles's law to complete the following table (assume pressure and number of moles of gas to be constant):
| V1 | T1 | V2 | T2 |
| 117L | 11.3?C | -- | 120.4?C |
| -- | 129K | 174L | 308K |
| 2.13L | 14.4?C | 2.43L | -- |
| 15.9cm3 | -- | 19.9cm3 | 11.4?C |
In: Chemistry
To find the pKa of X-281, you prepare a 0.092M test solution of X-281. The pH of the solution is determined to be 2.40. What is the pKa of X-281?
In: Chemistry
Alchemists in the Middle Ages dreamed of converting base metals, such as lead, into precious metals—gold and silver. Why could they never succeed? Today could we convert lead to gold?
In: Chemistry
Match the following aqueous solutions with the
appropriate letter from the column on the right.
| 1. | 0.19 m | CuCl2 | A. | Lowest freezing point | ||
| 2. | 0.17 m | Ni(NO3)2 | B. | Second lowest freezing point | ||
| 3. | 0.16 m | K2S | C. | Third lowest freezing point | ||
| 4. | 0.54 m | Sucrose(nonelectrolyte) | D. | Highest freezing point |
another one:
Match the following aqueous solutions with the
appropriate letter from the column on the right.
| 1. | 0.16 m | CoCl2 | A. | Lowest freezing point | ||
| 2. | 0.17 m | CrCl2 | B. | Second lowest freezing point | ||
| 3. | 0.18 m | Mn(NO3)2 | C. | Third lowest freezing point | ||
| 4. | 0.46 m | Glucose(nonelectrolyte) | D. | Highest freezing point |
In: Chemistry
The reaction 2H2O2(aq)→2H2O(l)+O2(g)2H2O2(aq)→2H2O(l)+O2(g) is first order in H2O2H2O2 and under certain conditions has a rate constant of 0.00752 s−1s−1 at 20.0 ∘C∘C. A reaction vessel initially contains 150.0 mLmL of 30.0% H2O2H2O2 by mass solution (the density of the solution is 1.11 g/mLg/mL). The gaseous oxygen is collected over water at 20.0 ∘C∘C as it forms.
What volume of O2O2 will form in 62.8 seconds at a barometric pressure of 773.0 mmHg . (The vapor pressure of water at this temperature is 17.5 mmHg)
In: Chemistry
1. The pH of a 0.42M dimethylamine solution is:
A. 2.5 B.1.80 C.1.7 D.12.2
2.The pH of a buffer solution composed of 0.020M HClO and 0.014M NaClO is:
A.7.37 B. 7.52 C. 7.68
3.When a base is added to a buffer composed of HF and NaF , the OH- is neutralized by:
A. F- B. HF C. Water
4. calculate the solubility of iron(II) hydroxide at 25oC
| A. | 5.8 x 10-6 | |
| B. | 2.8 x 10-8 | |
| C. | 9.2 x 10-6 |
5.. The pH of a 0.0145M perchloric acid solution is:
A. 1.84 B. 7.0 C.12.2
6.When 400ml of a 0.01M CaCl solution is mixed with a 300ml if a NaOH solution at pH 9.0, a precipitate will form.
True Or False
In: Chemistry
What are the values for the spin-angular-momentum and the orientation of the spin- angular-momentum for a ground-state hydrogen electron? Sketch a picture to display the electron orientation.
In: Chemistry
A battery is constructed based on the oxidation of magnesium and the reduction of Cu2+. The initial concentrations of Mg2+ and Cu2+ are 1.1×10−4 M and 1.6 M , respectively, in 1.0-liter half-cells.
PART A: What is the initial voltage of the battery?
PART B: What is the voltage of the battery after delivering 4.7 A for 8.0 h ?
PART C: How long can the battery deliver 4.7 A before going dead?
In: Chemistry
What is the amount of Na2HPO4 you need to add to a solution of
25mg NaH2PO4 in 100ml water
to obtain a pH=7.95?
In: Chemistry
At SATP, Ethanol (C2H6O) is a liquid that has a density of 0.789 g/cm3 and a Gibbs energy of formation Gf =-174.78 kJ.mol-1 Use this information to calculate the chemical potential of ethanol at 298 K and 10.0 bar pressure assuming that the liquid volume is pressure-independent.
show in detail
In: Chemistry
Reagent Data Table. Fill in the missing values for each entry.
[4] note: if you were unable to determine the yield, you must give an example yield calculation
Table 1. Reagent and Yield Data for the synthesis of butyl acetate from cesium acetate.
Compound Amount MW (g/mol) mmoles Stoichiometry/Comments
acetaminophen 350 mg
ethyl iodide 300 µL
(d = g/mL)
NaOEt 2.6 mL
ethanol 2 mL
phenacetin product obtained: 0.0175 g
crude product yield1 =
recrystallized yield1 =
In: Chemistry
What is the pH of a solution made by adding 100g of sodium acetate to 500mL of water?
please answer in detail ,
In: Chemistry
Calculate ΔrxnS, ΔrxnH, and ΔrxnG at 298Kfor the reaction below:
2 C3H6 (g) -----------------> C2H4 (g) + C4H8 (g)
In: Chemistry
What is the change in enthalpy (in kJ) under standard conditions when 200.18 g of sodium sulfate dissolves in water?
In: Chemistry