Need help plzz

GIVING BRAINLIEST AND THE REST OF MY POINTS!!!!! :D

Alik [6]

It’s d I did this before

6 0

3 years ago

A 1.00 liter solution contains 0.43 M hydrofluoric acid and 0.56 M potassium fluoride. If 0.280 moles of potassium hydroxide are

kolbaska11 [484]

Answer:

Answers are in the explanation

Explanation:

Equlibrium of HF in H₂O is:

HF + H₂O ⇄ F⁻ + H₃O⁺

Now, the KOH reacts with HF, thus:

KOH + HF → F⁻ + H₂O

That means after reaction, concentration of HF decrease increasing F⁻ concentration.

Now, seeing the equilibrium, as moles of HF decrease and F⁻ moles increase, the equilibrium will shift to the left decreasing H₃O⁺ concentration.

For the statements:

A. The number of moles of HF will increase. FALSE. HF react with KOH, thus, moles of HF decrease

B. The number of moles of F- will decrease. FALSE. The reaction produce F⁻ increasing its moles.

C. The equilibrium concentration of H₃O⁺ will increase. FALSE. The equilibrium shift to the left decreasing concentration of H₃O⁺

D. The pH will decrease. FALSE. As the H₃O⁺ concentration decrease, pH will increase

E. The ratio of [HF] / [F-] will remain the same. FALSE. Because moles of HF are decreasing whereas F- moles are increasing changing, thus, ratio.

6 0

4 years ago

Compare a mixture and a compound. How are they alike?

harina [27]

Answer:

1.Difference.

Mixtures are physically combined and can be separated by physical means while compounds are chemically combined and are separated by chemical means.

2.Mixtures do not have mixed boiling and melting points while compounds have mixed boiling and melting points.

2.Similarity.

Both mixtures and compounds are composed of two or more substances or elements combined.

Both can be separated.

7 0

3 years ago

7.00 of Compound x with molecular formula C3H4 are burned in a constant-pressure calorimeter containing 35.00kg of water at 25c.

beks73 [17]

Answer:

$\Delta H_{f,C_3H_4}=276.8kJ/mol$

Explanation:

Hello!

In this case, since the equation we use to model the heat exchange into the calorimeter and compute the heat of reaction is:

$\Delta H_{rxn} =- m_wC_w\Delta T$

We plug in the mass of water, temperature change and specific heat to obtain:

$\Delta H_{rxn} =- (35000g)(4.184\frac{J}{g\°C} )(2.316\°C)\\\\\Delta H_{rxn}=-339.16kJ$

Now, this enthalpy of reaction corresponds to the combustion of propyne:

$C_3H_4+4O_2\rightarrow 3CO_2+2H_2O$

Whose enthalpy change involves the enthalpies of formation of propyne, carbon dioxide and water, considering that of propyne is the target:

$\Delta H_{rxn}=3\Delta H_{f,CO_2}+2\Delta H_{f,H_2O}-\Delta H_{f,C_3H_4}$

However, the enthalpy of reaction should be expressed in kJ per moles of C3H4, so we divide by the appropriate moles in 7.00 g of this compound:

$\Delta H_{rxn} =-339.16kJ*\frac{1}{7.00g}*\frac{40.06g}{1mol}=-1940.9kJ/mol$

Now, we solve for the enthalpy of formation of C3H4 as shown below:

$\Delta H_{f,C_3H_4}=3\Delta H_{f,CO_2}+2\Delta H_{f,H_2O}-\Delta H_{rxn}$

So we plug in to obtain (enthalpies of formation of CO2 and H2O are found on NIST data base):

$\Delta H_{f,C_3H_4}=3(-393.5kJ/mol)+2(-241.8kJ/mol)-(-1940.9kJ/mol)\\\\\Delta H_{f,C_3H_4}=276.8kJ/mol$

Best regards!

7 0

3 years ago

How is it that an electron can cause your brain to “see” color without ever leaving its atom?

iogann1982 [59]

Light receptors with in the eye transmit messages to the brain, which procedures is the familiar sensations of color. Newton observed that color is not inherit in objects. Rather the surface of an object reflects some colors and absorbs all the others. We perceive only the reflective colors.

4 0

3 years ago