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4 years ago

Describe the nucleus of an atom

1 answer:

monitta4 years ago

7 0

The nucleus is the center of an atom. It is made up of nucleons called (protons and neutrons) and is surrounded by the electron cloud. ... Almost all of the mass in an atom is made up from the protons and neutrons in the nucleus with a very small contribution from the orbiting electrons.

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A chemist adds of a sodium thiosulfate solution to a reaction flask. Calculate the mass in grams of sodium thiosulfate the chemi

schepotkina [342]

This is a incomplete question.The complete question is:

A chemist adds 180.0 ml of a 1.77 mol/L of sodium thiosulfate solution to a reaction flask. Calculate the mass in grams of sodium thiosulfate the chemist has added to the flask. Be sure your answer has the correct number of significant digits.

Answer: 50.4 g

Explanation:

To calculate the number of moles for given molarity, we use the equation:

$\text{Moles of solute}={\text{Molarity of the solution}}\times{\text{Volume of solution (in L)}}$ .....(1)

Molarity of sodium thiosulfate solution = 1.77 M

Volume of sodium thiosulfate solution = 180.0 mL = 0.1800 L

Putting values in equation 1, we get:

$\text{Moles of sodium thiosulfate}={1.77}\times{0.1800}=0.319moles$

Mass of sodium thiosulfate = $moles\times {\text {Molar mass}}=0.319moles\times 158.11g/mol=50.4g$

Thus 50.4 g of sodium thiosulfate the chemist has added to the flask.

6 0

3 years ago

Ferrophosphorus (Fe2P) reacts with pyrite (FeS2) producing iron(II) sulfide and a compound that is 27.87% P and 72.13% S by mass

Shtirlitz [24]

Ferrophosphorus (Fe2P) reacts with pyrite (FeS2) producing iron(II) sulfide and a compound that is 27.87% P and 72.13% S by mass and has a molar mass of 444.56 g/mol of anxiety (low vs. high) and stress (low vs. moderate vs. high) on test.

Everyone experiences anxiety occasionally, but persistent anxiety can reduce your quality of life. Though Ferrophosphorus best known for altering behavior, worry can have negative effects on our physical health. Anxiety speeds up our heartbeat and breathing, concentrating blood flow to the parts of our brains that need it. You are getting ready for a challenging situation by having this extremely bodily reaction. Test performance may be impacted Ferrophosphorus anxiety. According to studies, pupils with low levels of test anxiety perform better on multiple-choice question (MCQ) exams than pupils with high levels of anxiety. Studies have indicated that female students have greater levels of test anxiety than male students.

Learn more about anxiety here:

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7 0

2 years ago

1. which volume has the most uncertainty associated wit the measurement?

Mamont248 [21]

1. The option a. 10 mL has the most uncertainty associated with it, because it has only 2 significative figures, while 10.0 mL has three significant figures and 10.00 has four significant figures.

2. The volume of solution that remains is 145.675 mL - 24.2 mL = 121.475 mL rounded to one decimal = 121.5 mL, given that the measure with the most uncerntainty has only one decimal.

4 0

4 years ago

Find the cell potential for a system whose ∆G = +55 kJ and 3 moles of electrons are exchanged.

rosijanka [135]

Answer:- cell potential = -0.19 volts

Solution:- The equation that shows the connection between $\Delta G$ and cell potential, E is written as:

$\Delta G=-nFE$

in this equation, n stands for moles of electrons, E stands for cell potential and F stands for faraday constant and it's value is $\frac{96485C}{mol}$ .

It asks to calculate the value of E, so let's rearrange the equation:

$E=-\frac{\Delta G}{nF}$

Let's plug in the values in it:

$E=-\frac{55kJ}{3mol*96485C.mol^-}$

$E=-\frac{0.00019kJ}{C}$

since, $\frac{1kJ}{C}=1000V$

Where C stands for coulombs and V stands for volts.

So, $E=-\frac{0.00019kJ}{C}(\frac{1000V}{\frac{1kJ}{C}})$

E = -0.19 V

So, the cell potential is -0.19 volts.

4 0

3 years ago

What mass of copper is equivalent to 0.7moles?

Shkiper50 [21]

I hope thus equations help

1. How many atoms are in 6.5 moles of zinc?
1 mole = atomic mass (g)
6.5 moles 6.02 x 1023 atoms = 3.9 x 1024 atoms 1 mole
2. How many moles of argon are in a sample containing 2.4 x 1024 atoms of argon?
2.4 x 1024 atoms of argon 1 mole
6.02 x 1023 atoms
3. How many moles are in 2.5g of lithium?
2.5 grams Li 1 mole 6.9 g
4. Findthemassof4.8molesofiron.
4.8 moles 55.8 g 1 mole
= 4.0 mol
= 0.36 mol
= 267.84 g = 270g

1 mole = 6.02 x 1023 atoms 1 mole = atomic mass (g)
MASS (g)
1 mole = molar mass (look it up on the PT!)
MOLE
1 mole = 6.02 x 1023 atoms
PARTICLES (ATOM)
Two Step Problems:
1. What is the mass of 2.25 x 1025 atoms of lead?
2.25 x 1025 atoms of lead 1 mole 207.2g = 6.02 x 1023 atoms 1 mole
2. How many atoms are in 10.0g of gold?
10 g gold 1 mole 6.02 x 1023 atoms = 197.0g 1 mole
PRACTICE PROBLEMS:
1. How many moles are equal to 625g of copper?
625g of copper 1 mol = 9.77 mol Cu 64 g Cu
7744.19g = 7740g
3.06 x 1022 atoms
2. How many moles of barium are in a sample containing 4.25 x 1026 atoms of barium?
4.25 x 1026 atoms of barium 1 mol = 706 mol 6.02 x 1023 atoms
3. Convert 2.35 moles of carbon to atoms.
2.35 moles 6.02 x 1023 atoms = 1.41 x 1024 atoms 1 mole
4. How many atoms are in 4.0g of potassium?
4.0 g 1 mole 6.02 x 1023 atoms = 6.2 x 1022 atoms 39.1 g 1 mole

1 mole = 6.02 x 1023 atoms 1 mole = atomic mass (g)
5. Convert 9500g of iron to number of atoms in the sample.
9500 g Fe 1 mole 6.02 x 1023 atoms = 55.8g 1 mole
6. What is the mass of 0.250 moles of aluminum?
0.250 moles 27.0g = 6.75 g Al 1 mole
7. How many grams is equal to 3.48 x 1022 atoms of tin?
3.48 x 1022 atoms 1 mole 118.7g 6.02 x 1023 atoms 1 mole
8. What is the mass of 4.48 x 1021 atoms of magnesium?
4.48 x 1021 atoms 1 mole 24.3g 6.02 x 1023 atoms 1 mole
9. Howmanymolesis2.50kgoflead?
2.50kg 1000 g 1 mol 1 kg 207.2 g
1.0 x 1026 atoms
= 6.86 g Sn
= 0.181 g Mg or 1.8 x 10-1
= 12.1 mol
10.Find the mass, in cg, of 3.25 x 1021 atoms of lithium.
3.25 x 1021 atoms 1 mol 6.9g 100cg 6.02 x 1023 atoms 1 mol 1 g
= 3.7 cg

7 0

3 years ago