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3 years ago

What is the atomic number of an atom that has 20 protons and 20 neutrons

Chemistry

1 answer:

vladimir2022 [97]3 years ago

5 0

Answer:

Explanation:

Hi there!

We need to find the atomic number of an atom that has 20 protons and 20 neutrons

the atomic number of an atom is equivalent to the amount of protons an atom has, as the number of protons determines what element an atom is.

Since the atom has 20 protons, the atomic number of the said atom is 20

Hope this helps!

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A certain substance melts at a temperature of . But if a sample of is prepared with of urea dissolved in it, the sample is found

pshichka [43]

Answer:

2.2 °C/m

Explanation:

It seems the question is incomplete. However, this problem has been found in a web search, with values as follow:

" A certain substance X melts at a temperature of -9.9 °C. But if a 350 g sample of X is prepared with 31.8 g of urea (CH₄N₂O) dissolved in it, the sample is found to have a melting point of -13.2°C instead. Calculate the molal freezing point depression constant of X. Round your answer to 2 significant digits. "

So we use the formula for freezing point depression:

ΔTf = Kf * m

In this case, ΔTf = 13.2 - 9.9 = 3.3°C

m is the molality (moles solute/kg solvent)

350 g X ⇒ 350/1000 = 0.35 kg X

31.8 g Urea ÷ 60 g/mol = 0.53 mol Urea

Molality = 0.53 / 0.35 = 1.51 m

So now we have all the required data to solve for Kf:

ΔTf = Kf * m

3.3 °C = Kf * 1.51 m

Kf = 2.2 °C/m

5 0

3 years ago

What is the molarity of a 4.447 L solution

igomit [66]

Answer:52M

Explanation:

use S= 1000w/ MV

Here, s= molarity

w= the amount of NaCl

M= the atomic mass of NaCl

V= the volume of solution

4 0

3 years ago

Exactly one mole of an ideal gas is contained in a 2.00-liter container at 1,000 K. What is the pressure exerted by this gas?

levacccp [35]

Use PV =nRT

so P = nRT/V

= 1 mole(0.08205 L atm/K mol)(1000K) / 2 L

= 41 atm

7 0

3 years ago

Read 2 more answers

Which law suggests that at a constant pressure, the volume of gas is directly proportional to its temperature?

igor_vitrenko [27]

Answer:

The law that suggests that at a constant pressure and the volume of gas directly proportional to its temperature is the Boyle's law.

Explanation:

4 0

2 years ago

In the laboratory a student uses a "coffee cup" calorimeter to determine the specific heat of a metal. She heats 19.6 grams of z

storchak [24]

Answer:

The specific heat of zinc is 0.375 J/g°C

Explanation:

Step 1: Data given

Mass of zinc = 19.6 grams

Mass of water = 82.9 grams

Initial temperature of zinc T1= 98.37 °C

Initial temperature of water T1= 24.16 °C

Final temperature of water (and zinc) T2 = 25.70 °C

Specific heat of water = 4.184 J/g°C

Step 2: Calculate Specific heat of zinc

Q=m*c*ΔT

Qzinc = -Qwater

m(zinc)*C(zinc)*ΔT(zinc) = -m(water)*C(water)*ΔT(water)

⇒ with mass of water = 82.9 grams

⇒ with C(water) = 4.184 J/g°C

⇒ with ΔT(water) = T2 - T1 = 25.70 - 24.16 = 1.54

⇒ with mass of zinc = 19.6 grams

⇒ with C(zinc) = TO BE DETERMINED

⇒ with ΔT(zinc) = T2 -T1 = 25.70 - 98.37 = -72.67°C

Qzinc = -Qwater

m(zinc)*c(zinc)* ΔT(zinc) = - m(water)*c(water)* ΔT(water)

19.6g* C(zinc) * (-72.67°C) = - 82.9g* 4.184 J/g°C * 1.54 °C

-1424.332*C(zinc) = -534.155

C(zinc) = 0.375 J/g°C

The specific heat of zinc is 0.375 J/g°C

4 0

3 years ago