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Serggg [28]
2 years ago
9

A 20.0 gram sample of an element contains 4.95 x 1023 atoms. what is the element?

Chemistry
1 answer:
Sonja [21]2 years ago
7 0
You will want to find how many grams are in a whole mole so you know which element it is. To do this, find out how much of a mole you have.

4.95 x 10^23 atoms / 6.022 x 10^23 atoms (one whole mole of any element) = .8219860511 or ~82% of 1 mole

Now we know that, find what to multiply 20 g by to get the rest of the mole.

1 mole / .8219860511 mole = 1.216565657

20 g x 1.216565657 = ~24.33 g / mol

Now that you have grams per mole, you can look at the periodic table and the molar masses to see which this number is closely aligned.

Your answer is Magnesium (Mg), which has a molar mass of 24.305 g


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A student was given four unknown solutions. Each solution was checked for. conductivity and tested with. phenolphthalein. The re
777dan777 [17]

Answer: (3) C

Explanation:

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2 years ago
What is the mass of bromine gas if it has a pressure of 720 mmHg, volume of 25mL and a temperature of 18.3 degrees Celsius
Annette [7]

Answer:

             Mass = 0.158 g

Explanation:

Formula used,

P V = n R T

Or,

n = P V / R T

Putting values,

n = 0.948 atm . 0.025 L / 0.0821 L.atm.K⁻¹.mol⁻¹ . 291.45

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Note: we have changed pressure from mmHg to atm, volume from mL to L and temperature from C to K)

Also,

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Mass = 0.158 g

7 0
1 year ago
4. When 1.00 L of 1.00 M Ba(NO3)2 solution at 25.0˚C is mixed with 1.00 L of 1.00 M Na2SO4 solution at 25.0˚C in a calorimeter,
myrzilka [38]

Answer:

The final temperature of the mixture is 28.11 °C

Explanation:

Step 1: Data given

Volume of 1.00 M Ba(NO3)2 = 1.00 L

Temperature = 25.0 °C

Volume of 1.00 M Na2SO4 = 1.00 L

enthalpy change is – 26 kJ per mol BaSO4

The specific heat of water is 4.18 J/g ·˚C

the density of water is 1.00 g/mL

Step 2: The balanced equation

Ba(NO3)2(aq) + Na2SO4(aq) → 2NaNO3(aq) + BaSO4(s)

Step 3: Calculate the total volume

Total volume = 1.00 L + 1.00 L = 2.00 L = 2000 mL

Step 4: Calculate mass

Mass = volume * density

Mass = 2000 mL * 1g/mL

Mass = 2000 grams

Step 5: Calculate moles BaSO4 formed

For 1 mol Ba(NO3)2 we need 1 mol Na2SO4 to produce 1 mol BaSO4

There is no limiting reactant, both Ba(NO3)2 and Na2SO4 will be completely be consumed (1 mol). We'll have 1.0 mol of BaSO4 produced.

Step 6: Calculate Q

Q = - ΔH

ΔH is negative so the reaction is exothermic, what means the temperature increases

Q is always positive, so Q = 26kJ = 26000 J

Step 6: Calculate the heat transfer

Q= m*c*ΔT

⇒with Q = the heat transfer = TO BE DETERMINED

⇒with m =the mass of the solution = 2000 grams

⇒with c= the specific heat of the solution = 4.18 J/g°C

⇒with ΔT = the change of temperature = T2 - T1 = T2 - 25.0

26000 = 2000 * 4.18 * (T2 - 25.0 °C)

3.11 = T2 - 25.0 °C

T2 = 25.0 + 3.11 °C

T2 = 28.11 °C

The final temperature of the mixture is 28.11 °C

7 0
3 years ago
If your car gets 30.3 mi/gal, how many gallons of gasoline would you use if you drove 506.3 miles? 1 mile = 5280 ft (exactly) In
Salsk061 [2.6K]

Answer: 16.7 gallon

Explanation:

Given: The car can drive 30.3 miles when 1 gallon of gasoline is used.

Distance covered = 506.3 miles

Thus for 30.3 miles, the amount of gasoline used= 1 gallon

For 506.3 miles, the amount of gasoline used=\frac{1}{30.3}\times 506.3=16.7gallon

Thus the amount of gasoline used is 16.7 gallons.


4 0
3 years ago
Read 2 more answers
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