CHEM 1100 Lecture Notes - Lecture 13: Sulfuric Acid, Ammonia, Lead

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24 Oct 2017

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Electrolytes: conducts electricity when dissolved in water, nonelectrolytes do not conduct electricity, why do some conduct but not others, conductivity = due to ions in solution, electrolyte--ionized! ***more ions = better conductivity: nacl (s) na+ (aq) + cl- (aq) Ion attraction too great for h2o to break: won"t dissolve (much) Group 1 metals and nh4: soluble covalents, sugar, ethanol, covalent compounds, soluble, nonelectrolytes, how, have o-h groups, form h-bonds w h2o. Like dissolves like : polar dissolves polar; nonpolar dissolves nonpolar, nacl (polar ionic) - soluble, sugar (polar) - soluble (form h-bonds, oil (nonpolar) - insoluble, no poles , chcl3 (polar) - insoluble, can"t form hydrogen bonds. Blue baby syndrome: lead and chlorine, toxic, nacl (salt, can lead to high blood pressure. Acids and bases: can be strong acids, weak acids, strong bases, and weak bases, strong/weak det by how they react w h2o, strong bases and strong acids ionize completely.

Related Questions

Â± 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 20âC.

Fortunately, there are several other ways of expressing concentration that do not involve volume and are therefore temperature independent.

A 2.350Ã10^â2M solution of NaCl in water is at 20.0âC. 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 20.0âC 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.

mNaCl =

.0235m

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Incorrect; Try Again; no points deducted

Your answer has units of mol/L of water. You need to convert the volume of water to kilograms using the density provided.

Part B

Calculate the mole fraction of salt in this solution.

Express the mole fraction to four significant figures.

ÏNaCl =

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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.

percent by mass NaCl =

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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.

parts per million NaCl =

ppm

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sapphirespider251

3a. If the molar absorptivity constant for the red dye solution is 5.56Ã104 M-1 cm-1 , calculate the molarity of the red dye solution with absorption = 0.900. You may assume L = 1.22cm. Hint: A=ÎµLC

b. Convert the molarity in part a to w/v%. Show your work. Molar mass of FD&C red #3 = 879.86g/mol w/v% is defined as weight (in grams) of solute/100 mL of solution You should remember that w/v% always refers to the grams of materials in 100mL of solution. ppm is defined as mg of solute/ L of solution (1mg = 10-3 g) ppb is defined as Âµg of solute / L of solution (1Âµg = 10-6 g)

c. If you want to dilute the red dye solution in part a by 5 times in a single dilution step, explain in two sentences on how one should proceed with the dilution. In addition, what is the final concentration of the diluted solution? Show your work for the numerical part of this question. You are only allowed to use a 5-mL volumetric pipet, a 10-mL volumetric pipet, a 50-mL volumetric flask and/or a 100-mL volumetric flask during the dilution. You may NOT reuse the same pipet during the dilution.

CHEM 1100 Lecture Notes - Lecture 13: Sulfuric Acid, Ammonia, Lead

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