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2 years ago

The Kelvin temperature required for 0.0470 mol of helium gas to fill a balloon to 1.20 L under 0.878 atm is

1 answer:

7 0

From the ideal gas law, PV = nRT, we can rearrange the equation to solve for T given the other parameters.

T = PV/nR

where P = 0.878 atm, V = 1.20 L, n = 0.0470 moles, and R = 0.082057 L•atm/mol•K. Plugging in our values, we obtain the temperature in Kelvin:

T = (0.878 atm)(1.20 L)/(0.0470 mol)(0.082057 L•atm/mol•K)
T = 273 K

So, the second answer choice would be correct.

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In the laboratory, a general chemistry student measured the pH of a 0.529 M aqueous solution of phenol (a weak acid), C6H5OH to

Artyom0805 [142]

Answer:

The dissociation constant of phenol from given information is $9.34\times 10^{-11}$ .

Explanation:

The measured pH of the solution = 5.153

$C_6H_5OH\rightarrow C_6H_5O^-+H^+$

Initially c

At eq'm c-x x x

The expression of dissociation constant is given as:

$K_a=\frac{[C_6H_5O^-][H^+]}{[C_6H_5OOH]}$

Concentration of phenoxide ions and hydrogen ions are equal to x.

$pH=-\log[x]$

$5.153=-\log[x]$

$x=7.03\times 10^{-6} M$

$K_a=\frac{x\times x}{(c-x)}=\frac{x^2}{(c-x)}=\frac{(7.03\times 10^{-6} M)^2}{ 0.529 M-7.03\times 10^{-6} M}$

$K_a=9.34\times 10^{-11}$

The dissociation constant of phenol from given information is $9.34\times 10^{-11}$ .

4 0

3 years ago

Is temperature beginning to rise a physical or chemical change?

Lelu [443]

Answer:

If temperature increases, as it does in most reactions, a chemical change is likely to be occurring. This is different from the physical temperature change. During a physical temperature change, one substance, such as water is being heated.

Explanation:

6 0

2 years ago

Read 2 more answers

What distinguishes a substance from a mixture?

wariber [46]

A mixture consists of numerous substances, whereas a substance does not consist of mixtures, but rather of compounds. Mixtures can be separated physically, while substances cannot.

4 0

3 years ago

How many atoms of hydrogen-1 are in a 1.007-g sample?

Greeley [361]

I think it's 2 I tried looking it up because I was not sure.

8 0

2 years ago

Which statement about AHf is true?

Pachacha [2.7K]

Answer:

It is positive when the bonds of the product store more energy than those of the reactants.

Explanation:

The standard enthalpy of formation, ΔHf, is defined as the energy required to form 1 mole of a substance from its contituent elements under standard conditions of pressure and temperature.

Then, per defintion, when the elements are already at their standard states, there is not energy involved to form them from that very state; this is, the standard enthalpy of formation of the elements in their standard states is zero.

It is not zero for the compounds in its standard state, because energy should be released or absorbed to form the compounds from their consituent elements. Thus, the first choice is false.

When the bonds of the products store more energy than the those of the reactants, the difference is:

ΔHf = ΔHf products - ΔHf reactants > 0, meaning that ΔHf is positive. Hence, the second statement is true.

Third is false because forming the compounds may require to use (absorb) or release (produce) energy, which means that ΔHf could be positive or negative.

Fourth statement is false, because the standard state of many elements is not liquid. For example, it is required to supply energy to iron to make it liquid. Thus, the enthalpy of formation of iron in liquid state is not zero.

3 0

3 years ago