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Natali5045456 [20]
4 years ago
9

100 POINTS ANSWER HURRY

Chemistry
2 answers:
rjkz [21]4 years ago
8 0
A pure substance is different from a mixture because D. mixtures can be separated by physical means. You can eliminate all of the other answers to find this out. A is incorrect because a pure substance is just that, a pure substance, while a mixture is multiple substances. B is incorrect because a pure substance is one substance, while heterogeneous is a type of mixture, which has multiple substances. And C is incorrect because a mixture is a blend of 2 or more substances.
Zigmanuir [339]4 years ago
5 0
The correct answer would be:

D. Mixtures can be separated by physical means. 
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The ph of a solution containing 0.818 M acetic acid<br> (ka1.76*10-5) ans 0.172 M sodium acetate is?
kvasek [131]

Explanation:

It is known that the relation between pH and pK_{a} is as follows.

              pH = pK_{a} + log \frac{[salt]}{[acid]}

and,     pK_{a} = -log K_{a}

Hence, first we will calculate the value of pK_{a} as follows.

                   pK_{a} = -log K_{a}

                               = -log (1.76 \times 10^{-5}

                               = 4.75

Now, we will calculate the value of pH as follows.

              pH = pK_{a} + log \frac{[\text{sodium acetate}]}{\text{acetic acid}}

                    = 4.75 + log \frac{0.172}{0.818}      

                    = 4.75 + (-0.677)

                    = 4.07

Therefore, we can conclude that the pH of given solution is 4.07.

5 0
4 years ago
What are examples of chemical change
VladimirAG [237]

Answer:

Almost everything in our surroundings represent chemical change

Explanation:

●Rusting of iron in presence of moisture and oxygen.

●Burning of wood.

●Milk becoming curd.

●Formation of caramel from sugar by heating.

●Baking of cookies and cakes.

●Cooking any food.

●Acid-base reaction.

●Digestion of food.

3 0
3 years ago
It takes 167 s for an unknown gas to effuse through a porous wall and 99 s for the same volume of n2 gas to effuse at the same t
irakobra [83]

Answer : The molar mass of the unknown gas will be 79.7 g/mol


Explanation : To solve this question we can use graham's law;


Now we can use nitrogen as the gas number 2, which travels faster than gas 1;

So, 167 / 99 = 1.687 So the nitrogen gas is 1.687 times faster that the unknown gas 1

We can compare the rates of both the gases;


So here, Rate of gas 2 / Rate of gas 1 = \sqrt{(molar mass 1 / molar mass 2)}

Now, 1.687 = square root [\sqrt{(molar mass 1) / (28.01 g/mol N_{2})} ]


When we square both the sides we get;


2.845 = (molar mass 1) / (28.01 g/mol N2)


On rearranging, we get,


2.845 X (28.01 g/mol N2) = Molar mass 1

So the molar mass of unknown gas will be = 79.7 g/mol

3 0
3 years ago
How many liters of 0.37 M solution can be made with 29.53 grams of lithium fluoride.<br> (LiF)?
dsp73

Answer:

V = 3.1 L      

Explanation:

Given data:

Molarity of solution = 0.37 M

Mass of LiF = 29.53 g

Volume of solution = ?

Solution:

Number of moles of LiF:

Number of moles = mass/molar mass

Number of moles = 29.53 g/ 25.94g/mol

Number of moles = 1.14 mol

Volume:

Molarity = number of moles of solute / Volume in L

0.37 M = 1.14 mol / V

V = 1.14 mol / 0.37 M

V = 3.1 L         (M = mol/L)

4 0
3 years ago
Seans formula did not have any atmos of oxygen
Dafna1 [17]
What are you asking???? If the formula had no atoms of oxygen then......
8 0
3 years ago
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