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3 years ago

What does the average atomic mass on the periodic table tell you?

1 answer:

3 0

The atomic mass on the periodic table represents the sum of number of protons and number of neutrons.

Atomic mass = Number of protons + number of neutrons

Hope this helps!

You might be interested in

How many moles are in 87.62 grams of strontium?

Zielflug [23.3K]

Explanation:

it's one mole because the atomic mass is treated as molar mass and the atomic mass of strontium is 87.62 grams/mol

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3 years ago

How do carrier proteins transport substances across cell membranes?

stepan [7]

Transport of substances across cell membrane:
Carrier proteins facilitate transport of material across a membrane by changing its shape to allow a substance to pass through its membrane. It transports substances from high concentration to lower concentration levels.

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3 years ago

Biểu thức định luật Raoul là?

Dennis_Churaev [7]

Answer: Định luật Raoult là một định luật hóa học vật lý, với ý nghĩa trong nhiệt động lực học. Được thành lập bởi nhà hóa học người Pháp François-Marie Raoult vào năm 1887, nó nói rằng áp suất một phần của mỗi thành phần của một hỗn hợp chất lỏng lý tưởng bằng với áp suất hơi của thành phần tinh khiết nhân với phần nốt ruồi của nó trong hỗn hợp. Kết quả là, việc giảm áp suất hơi tương đối của dung dịch pha loãng của chất tan không lây bằng với phần nốt ruồi của chất tan trong dung dịch.

Explanation: hope this helps :)

5 0

3 years ago

Does red light have more energy than green light?

Fed [463]

HEY GUYS DONT WRITE THIS ANSWER OK ☝️☝️

BECAUSE SHE WAS COPIED FROM INTERNET 

YOU CAN CHECK THIS ANSWER IN INTERNET OK GUYS PLEASE TRUST ME 

3 0

3 years ago

What quantity (moles) of NaOH must be added to 1.0 L of 1.8 M HC2H3O2 to produce a solution buffered at pH = pKa? Ka = 1.8×10-5

Westkost [7]

Answer:

a) We have to add 0.9 mole NaOH to 1.0 L of 1.8 M HC2H3O2

b) We have to add 0.277 mole NaOH to 1.0 L of 1.8 M HC2H3O2

c) We have to add 1.16 mole NaOH to 1.0 L of 1.8 M HC2H3O2

Explanation:

a) What quantity (moles) of NaOH must be added to 1.0 L of 1.8 M HC2H3O2 to produce a solution buffered at pH = pKa?

Step 1: Data given

Volume of HC2H3O2 = 1.0 L

Molarity of HC2H3O2 = 1.8 M

Ka = 1.8*10^-5

ph = pK = -log(1.8*10^-5) = 4.74

Step 2:

Use the Henderson-Hasselbalch equation.

pH = pKa + log(A-/HA)

4.74 = 4.74 + log(A-/HA)

0 = log(A-/HA)

A-/HA = 1

Consider X = moles of NaOH added (and moles of A- formed)

Remaining moles of HA = 1.8 - X

moles of A- = X

HA = 1.8 - X

X/(1.8-X) = 1

X =0.9

We have to add 0.9 mole NaOH to 1.0 L of 1.8 M HC2H3O2

To control we can do the following equation:

4.74 = 4.74 + log(0.9/0.9) = 4.74

b) What quantity (moles) of NaOH must be added to 1.0 L of 1.8 M HC2H3O2 to produce a solution buffered at pH = 4.00?

Step 1: Data given

Volume of HC2H3O2 = 1.0 L

Molarity of HC2H3O2 = 1.8 M

Ka = 1.8*10^-5

ph = 4

Step 2:

Use the Henderson-Hasselbalch equation.

pH = pKa + log(A-/HA)

4 = 4.74 + log(A-/HA)

-0.74 = log(A-/HA)

A-/HA = 0.182

Consider X = moles of NaOH added (and moles of A- formed)

Remaining moles of HA = 1.8 - X

moles of A- = X

HA = 1.8 - X

X/(1.8-X) = 0.182

X =0.277

We have to add 0.277 mole NaOH to 1.0 L of 1.8 M HC2H3O2

To control we can do the following equation:

4 = 4.74 + log(0.277/1.523)

c) What quantity (moles) of NaOH must be added to 1.0 L of 1.8 M HC2H3O2 to produce a solution buffered at pH = 5.00

Step 1: Data given

Volume of HC2H3O2 = 1.0 L

Molarity of HC2H3O2 = 1.8 M

Ka = 1.8*10^-5

ph = 5

Step 2:

Use the Henderson-Hasselbalch equation.

pH = pKa + log(A-/HA)

5 = 4.74 + log(A-/HA)

0.26 = log(A-/HA)

A-/HA = 1.82

Consider X = moles of NaOH added (and moles of A- formed)

Remaining moles of HA = 1.8 - X

moles of A- = X

HA = 1.8 - X

X/(1.8-X) = 1.82

X =1.16

We have to add 1.16 mole NaOH to 1.0 L of 1.8 M HC2H3O2

To control we can do the following equation:

5 = 4.74 + log(1.16/0.64) = 5

3 0

4 years ago