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2 years ago

What is the speed of a car that covers 250 miles in 5 hours?

1 answer:

5 0

250miles is distance
5hours is time
Speed = distance/time
Speed = 250/5
Speed =50miles per hour
50mph

Hope that helps :)

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What is the mass of arsenic that is contained in a 50.0 g sample if the concentration is 5 ppm?

faltersainse [42]

Answer: The mass of arsenic found in the sample is 0.25 mg

Explanation:

ppm is the amount of solute (in milligrams) present in kilogram of a solvent. It is also known as parts-per million.

To calculate the ppm of oxygen in sea water, we use the equation:

$\text{ppm}=\frac{\text{Mass of solute}}{\text{Mass of solution}}\times 10^6$

Both the masses are in grams.

We are given:

Concentration of arsenic = 5 ppm

Mass of sample = 50 g

Putting values in above equation, we get:

$5=\frac{\text{Mass of arsenic}}{50g}\times 10^6\\\\\text{Mass of arsenic}=\frac{5\times 50}{10^6}=0.00025g=0.25mg$

Conversion factor used: 1 g = 1000 mg

Hence, the mass of arsenic found in the sample is 0.25 mg

5 0

3 years ago

Which best describes the act of using senses or tools to gather information? creating a hypothesis making an observation summari

MAXImum [283]

Answer:

making an observation

Explanation:

its the right answer

3 0

3 years ago

5.0 km into miles (show work)

Pie

Answer:

5 km = 3.107 miles

one Kilometer is equal to 0.621371 meters

so the equation is

5 km times 0.621371 m

is equal to 3.107

7 0

2 years ago

Free-energy change, ΔG∘, is related to cell potential, E∘, by the equationΔG∘=−nFE∘where n is the number of moles of electrons t

mart [117]

Answer:

a) $\Delta G=372490 J$

b) $\Delta G=-568614 J$

Explanation:

a) The reaction:

$Mg(s) +Fe^{2+}(aq) \longrightarrow Mg^{2+}(aq) + Fe(s)$

The free-energy expression:

$\Delta G=-n*F*E$

$E=E_{red}-E_{ox]$

The element wich is reduced is the Fe and the one that oxidates is the Mg:

$-0.44V=E_{red}-(-2.37V)=1.93V$

The electrons transfered (n) in this reaction are 2, so:

$\Delta G=-2mol*96500 C/mol * 1.93 V$

$\Delta G=-372490 J$

b) If you have values of enthalpy and enthropy you can calculate the free-energy by:

$\Delta G=\Delta H - T* \Delta S$

with T in Kelvin

$\Delta G=-675 kJ*\frac{1000J}{kJ} - 298K*-357 J/K$

$\Delta G=-568614 J$

7 0

2 years ago

Boron sulfide, B2S3(s), reacts violently with water to form dissolved boric acid (H3BO3) and hydrogen sulfide gas.Express your a

ioda

Answer:

Explanation:

From the statement of the problem,

B₂S₃ $_{s}$ + H₂O $_{l}$ → H₃BO₃ $_{aq}$ + H₂S $_{g}$

B₂S₃ + H₂O → H₃BO₃ + H₂S

We that the above expression does not conform with the law of conservation of mass:

To obey the law, we need to derive a balanced reaction equation:

Let us use the mathematical method to obtain a balanced equation.

let the balanced equation be:

aB₂S₃ + bH₂O → cH₃BO₃ + dH₂S

where a, b, c and d will make the equation balanced.

Conservating B: 2a = c

S: 3a = d

H: 2b = 3c + 2d

O: b = 3c

if a = 1,

c = 2,

b = 6,

2d = 2(6) - 3(2) = 6, d = 3

Now we can input this into our equation:

B₂S₃ + 6H₂O → 2H₃BO₃ + 3H₂S

B₂S₃ $_{s}$ + 6H₂O $_{l}$ → 2H₃BO₃ $_{aq}$ + 3H₂S $_{g}$

4 0

2 years ago