solutions

Specific gravity
In the laboratory, specific gravity is used both in the description of concentrated solution(typically acids) and in the determination of the amount of solutes present in urine. Specific gravity is a description of density, which is an expression of the amount of mass per volume; specific gravity measurements depend on the number of solutes present as well as the mass of the solutes in a given volume.
Expressions of Concentration
Molarity Another method of describing the concentration of a solute within a solution is through the determination of the relative number of reactant particles (the solute) involved in a reaction mixture (the solution). This number is referred to as the molarity of the solute within the solution, and it describes the number of moles of solute in a specific amount of solution.

P ( X = k ) = P (Y + Z = k ) = ∑ P (Y = m, Z = k − m )
m=0 k k
= ∑ P (Y = m )P ( Z = k − m )
m=0 k m m = ∑ Cn p (1 − p) m=0 k n−m k −m k −m × Cn (1 − p) −m p n − m −( k − m )
therefore,
P ({M = 2, Z = 0}) =
3 1 = 36 12 P ({S = 5, Z = 1}) = 0 P ({S = 8, Z = 1}) = 2 1 = 36 18
(c) Since P ( M = 2 ) =
3 1 25 = , P ( Z = 0) = , and that 36 12 36 1 1 25 ≠ × = P ( M = 2) P ( Z = 0) 12 12 36
F (2) = P ( X ≤ 2) = P ( X = 2)
For the event X = 2 , the sample space is
F (1) = P ( X ≤ 1) = P ( X = 1) = P ( Φ ) = 0
⎧ ⎪ ⎪ ⎪ ⎪ Ω=⎨ ⎪ ⎪ ⎪ ⎪ ⎩
(1, 1), ( 2, 1), (3, 1), ( 4, 1), ( 5, 1), ( 6, 1),
1 2
FX (π − 3) = P ( X ≤ π − 3) = P ( X = −1) + P ( X = 0 ) = FY (1) = P (Y ≤ 1) = P (Y = 0 ) + P (Y = 1) = 3⎞ 1 ⎛ 3⎞ ⎛ FY ⎜ ⎟ = P ⎜ Y ≤ ⎟ = P (Y = 0 ) = ⎝ 4⎠ ⎝ ⎠ 4 8 FY (π − 3) = P (Y ≤ π − 3) = P (Y = 0 ) = 1 8 1 2

Solutions - Chapter 1010-1: Learning PythonOpen a blank file in your text editor and write a few lines summarizing what you’ve learned about Python so far. Start each line with the phrase In Python you can… Save the file as learning_python.txt in the same directory as your exercises fro mthis chapter. Write a program that reads the file and prints what you wrote three times. Print the contents once by reading in the entire file, once by looping over the file object, and once by storing the lines in a list and then working with them outside the with block.learning_python.txt:learning_python.py:Output:10-2: Learning CYou can use the replace() method to replace any word in a string with a different word. Here’s a quick example showing how to replace 'dog' with 'cat' in a sentence:Read in each line from the file you just created, learning_python.txt, and replace the word Python with the name of another language, such as C. Print each modified line to the screen.Output:You can use rstrip() and replace() on the same line. This iscalled chaining methods. In the following code the newline is stripped from the end of the line and then Python is replaced by C. The output is identical to the code shown above.10-3: GuestWrite a program that prompts the user for their name. When they respond, write their name to a file called guest.txt.Output:guest.txt:10-4: Guest BookWrite a while loop that prompts users for their name. When they entertheir name, print a greeting to the screen and add a line recording their visit in a file called guest_book.txt. Make sure each entry appears on a new line in the file.Output:guest_book.txt:10-5: Programming PollWrite a while loop that asks people why they like programming. Eachtime someone enters a reason, add their reason to a file that stores all the responses.Output:programming_poll.txt:10-6: AdditionOne common problem when prompting for numerical input occurs when people provide text instead of numbers. When you try to convert the input to an int, you’ll get a ValueError. Write a program that prompts for two numbers. Add them together and print the result. Catch the TypeError if either input value is not a number, and print a friendly error message. Test your program by entering two numbers and then by entering some text instead of a number.Output with two integers:Output with non-numerical input:10-7: Addition CalculatorWrap your code from Exercise 10-6 in a while loop so the user cancontinue entering numbers even if they make a mistake and enter text instead of a number.Output:10-8: Cats and DogsMake two files, cats.txt and dogs.txt. Store at least three names ofcats in the first file and three names of dogs in the second file. Write a program that tries to read these files and print the contents of the file to the screen. Wrap your code ina try-except block to catchthe FileNotFound error, and print a friendly message if a file is missing. Move one of the files to a different location on your system, and make sure the code in the except block executes properly.cats.txt:dogs.txt:cats_and_dogs.py:Output with both files:Output after moving cats.txt:10-9: Silent Cats and DogsModify your except block in Exercise 10-8 to fail silently if either file is missing.Output when both files exist:Output when cats.txt has been moved:10-11: Favorite NumberWrite a program that prompts for the user’s favorite number.Use json.dump() to store this number in a file. Write a separateprogram that reads in this value and prints the message, “I know your favorite number! It’s _____.”favorite_number_write.py:Output:favorite_number_read.py:Output:10-12: Favorite Number RememberedCombine the two programs from Exercise 10-11 into one file. If the number is already stored, report the favorite number to the user. If not, prompt for the user’s favorite number and store it in a file. Run the program twice to see that it works.Output, first run:Output, second run:10-13: Verify UserThe final listing for remember_me.py assumes either that the user has already entered their username or that the program is running for the first time. We should modify it in case the current user is not the person who last used the program.Before printing a welcome back message in greet_user(), ask the user if this is the correct username. If it’s not,call get_new_username() to get the correct username.Output:You might notice the identical else blocks in this versionof greet_user(). One way to clean this function up is to use an empty return statement. An empty return statement tells Python to leave the function without running any more code in the function. Here’s a cleaner version of greet_user():The return statement means the code in the function stops running after printing the welcome back message. When the username doesn’t exist, or the username is incorrect, the return statement is never reached. The second part of the function will only run whenthe if statements fail, so we don’t need an else block. Now the function prompts for a new username when either if statement fails. The only thing left to address is the nested if statements. This can be cleaned up by moving the code that checks whether the username iscorrect to a separate function. If you’re enjoying this exercise, you might try making a new function called check_username() and see if you can remove the nested if statement from greet_user().。

It is impossible to see the component particles of solutions or colloid or to separate them by passing the sopaper.






The terms unsaturated, saturated and supersaturated may be applied to solutions in which the solute has a finite solubility in the solvent. Unsaturated solutions contain less solute per 100 ml of solvent than the solubility. Saturated solutions contain the amount of solute equal to the solubility. Supersaturated solutions actually more solute per 100 ml of solvent than the solubility would seem to allow. One way to make a supersaturated solution is to evaporate solvent from a solution very slowly and carefully without stirring.



There are two general types of homogeneous mixtures, which are distinguished from each other by the size of their component particles. Solutions are homogeneous mixtures in which the particle sizes of the components (molecules or ions) range from about 1.0 to 10 nm. Colloids contain component particles from 10 to 100nm in size.