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3 years ago

Which statement correctly describes an endothermic chemical reaction?

1 answer:

Natasha2012 [34]3 years ago

7 0

An endothermic chemical reactions products tend to have a higher potential energy than the reactants. Thus making the /\ H positive, not negative.

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A rigid tank contains 0.66 mol of oxygen (O2). Find the mass of oxygen that must be withdrawn from the tank to lower the pressur

dsp73

Answer:

12.8 g of $O_{2}$ must be withdrawn from tank

Explanation:

Let's assume $O_{2}$ gas inside tank behaves ideally.

According to ideal gas equation- $PV=nRT$

where P is pressure of $O_{2}$ , V is volume of $O_{2}$ , n is number of moles of $O_{2}$ , R is gas constant and T is temperature in kelvin scale.

We can also write, $\frac{V}{RT}=\frac{n}{P}$

Here V, T and R are constants.

So, $\frac{n}{P}$ ratio will also be constant before and after removal of $O_{2}$ from tank

Hence, $\frac{n_{before}}{P_{before}}=\frac{n_{after}}{P_{after}}$

Here, $\frac{n_{before}}{P_{before}}=\frac{0.66mol}{43atm}$ and $P_{after}=17atm$

So, $n_{after}=\frac{n_{before}}{P_{before}}\times P_{after}=\frac{0.66mol}{43atm}\times 17atm=0.26mol$

So, moles of $O_{2}$ must be withdrawn = (0.66 - 0.26) mol = 0.40 mol

Molar mass of $O_{2}$ = 32 g/mol

So, mass of $O_{2}$ must be withdrawn = $(32\times 0.40)g=12.8g$

7 0

3 years ago

How many moles of Al will be consumed when 0.400 mol of Al2O3 are produced in

Vladimir [108]

Answer:

C) 0.800 mol

Explanation:

4Al + 3O₂ → 2Al₂O₃

In order to convert from moles of Al₂O₃ into moles of Al, we'll need to use the stoichiometric coefficients, using a conversion factor that has Al₂O₃ moles in the denominator and Al moles in the numerator:

0.400 mol Al₂O₃ * $\frac{4molAl}{2molAl_2O_3}$ = 0.800 mol Al

So the correct answer is option C).

7 0

3 years ago

How an atom of an element reacts chemically is based on its what?

iragen [17]

How an atom reacts chemically depends on how willing it is to share electrons with others.

It’s electrons

8 0

3 years ago

In Chemistry, to be classified as an organic substance, a substance must contain

Natasha_Volkova [10]

I'm going on a limb here, but Carbon is a definite.

4 0

3 years ago

A ball is thrown straight up into the air with a speed of 13 m/s. If the ball has

nataly862011 [7]

Answer:

The total energy, i.e. sum of kinetic and potential energy, is constant.

i.e. E = KE + PE

Initially, PE = 0 and KE = 1/2 mv^2

At maximum height, velocity=0, thus, KE = 0 and PE = mgh

Since, total energy is constant (KE converts to PE when the ball is rising),

therefore, KE = PE

or, 1/2 mv^2 = mgh

or, h = v^2 /2g = 13^2 / (2x9.8) = 8.622 m

Hope this helps.

5 0

3 years ago