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3 years ago

How many moles of ethyl alcohol, C2H6O, are in a 27.0g sample

1 answer:

3 0

C=12 g/mole
H=1 g/mole
O=16 g/mole
2(12)+6(1)+16=46 g/mole C2H6O
46 g/27 g =1 mole/x mole⇒ x≈0.58
the answer is about 0.58. hope helped ;)

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Briefly describe the action of hardwater with soap

morpeh [17]

Answer:

The correct answer is - hard water reacts to form the calcium or magnesium salt of the organic acid of the soap.

Explanation:

Soaps are made up of fatty acids or oils by treating with strong alkali and are salts of sodium and potassium. Hard water, on the other hand, has a high concentration of minerals in comparison to soft water. When hard water and soap are mixed together the salts of the minerals like Ca2+ and Mg2+ ions present in hard water react with fatty acids of the soap.

The sodium salts are changed to the salts of calcium and magnesium which are precipitated to an insoluble substance. The insoluble salts of the calcium or magnesium dirt stick on the clothes thus cleaning ability of soap is reduced.

4 0

3 years ago

50.00 mL of 0.10 M HNO 2 (nitrous acid, K a = 4.5 × 10 −4) is titrated with a 0.10 M KOH solution. After 25.00 mL of the KOH sol

boyakko [2]

Answer:

b. 3.35

Explanation:

To calculate the pH of a solution containing both acid and its salt (produced as a result of titration) we need to use Henderson’s equation i.e.

pH = pKa + log ([salt]/[acid]) (Eq. 01)

Where

pKa = -log(Ka) (Eq. 02)

[salt] = Molar concentration of salt produced as a result of titration

[acid] = Molar concentration of acid left in the solution after titration

Let’s now calculate the molar concentration of HNO2 and KOH considering following chemical reaction:

HNO2 + KOH ⇆ H2O + KNO2 (Eq. 03)

This shows that 01 mole of HNO2 and 01 mole of KOH are required to produce 01 mole of KNO2 (salt). And if any one of them (HNO2 and KOH) is present in lower amount then that will be considered the limiting reactant and amount of salt produced will be in accordance to that reactant.

Moles of HNO2 in 50 mL of 0.01 M HNO2 solution = 50/1000x0.01 = 0.005 Moles

Moles of KOH in 25 mL of 0.01 M KOH solution = 25/1000x0.01 = 0.0025 Moles

As it can be seen that we have 0.0025 Moles of KOH therefore considering Eq. 03 we can see that 0.0025 Moles of KOH will react with only 0.0025 Moles of HNO2 and will produce 0.0025 Moles of KNO2.

Therefore

Amount of salt produced i.e [salt] = 0.0025 moles (Eq. 04)

Amount of acid left in the solution [acid] = 0.005 - 0.0025 = 0.0025 moles (Eq.05)

Putting the values in (Eq. 01) from (Eq.02), (Eq. 04) and (Eq. 05) we will get the following expression:

pH= -log(4.5x10 -4) + log (0.0025/0.0025)

Solving above we get

pH = 3.35

5 0

4 years ago

What is the specific heat capacity of an unknown metal if 75.00 g of the metal absorbs 418.6J of heat and the temperature rises

EleoNora [17]

Answer:

The specific heat capacity of the unknown metal is 0.223 $\frac{J}{g*C}$

Explanation:

Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.

There is a direct proportional relationship between heat and temperature. The constant of proportionality depends on the substance that constitutes the body as on its mass, and is the product of the specific heat by the mass of the body. So, the equation that allows calculating heat exchanges is:

Q = c * m * ΔT

where Q is the heat exchanged by a body of mass m, made up of a specific heat substance c and where ΔT is the temperature variation.

In this case, you know:

Q= 418.6 J
c= ?
m= 75 g
ΔT= 25 C

Replacing:

418.6 J= c* 75 g* 25 C

Solving:

$c=\frac{418.6 J}{75 g*25 C}$

c= 0.223 $\frac{J}{g*C}$

The specific heat capacity of the unknown metal is 0.223 $\frac{J}{g*C}$

3 0

3 years ago

Sound waves are transverse mechanical waves. True False

allochka39001 [22]

False

Explanation:

Sound waves are longitudinal mechanical waves.

Mechanical waves are waves that requires a medium to propagate them.

A transverse wave is a wave that is propagated perpendicularly to its source.
An example is electromagnetic radiation.
A longitudinal wave is a wave that is directed parallel to their source.
Sound wave is a longitudinal wave.
It has series of rarefaction and compression along its travel path.
Rarefaction are areas of sparse particles.
Compression are areas with dense particles.

learn more:

Sound wave brainly.com/question/3619541

#learnwithBrainly

7 0

3 years ago

Nitroglycerine decomposes violently according to the chemical equation below. What mass of carbon dioxide gas is produced from t

Ulleksa [173]

Explanation:

Below is an attachment containing the solution.

5 0

4 years ago