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3 years ago

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#1: Which of the following is an exothermic reaction?

1 answer:

aleksandrvk [35]3 years ago

5 0

<span>An exothermic reaction is one in which heat is released from the reagents into the ambient environment. Perhaps somewhat counterintuitively, condensation is in fact an example of such a reaction. During the process of the gas-to-liquid phase change, water goes from a higher-energy to lower-energy state of matter, and, as such, releases heat into the environment.</span>

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A tetraphenyl phosphonium chloride (TPPCl) powder (FW=342.39) is 94.0 percent pure. How many grams are needed to prepare 0.45 L

slega [8]

Answer:

5.41 g

Explanation:

Considering:

$Molarity=\frac{Moles\ of\ solute}{Volume\ of\ the\ solution}$

Or,

$Moles =Molarity \times {Volume\ of\ the\ solution}$

Given :

For tetraphenyl phosphonium chloride :

Molarity = 33.0 mM = 0.033 M (As, 1 mM = 0.001 M)

Volume = 0.45 L

Thus, moles of tetraphenyl phosphonium chloride :

$Moles=0.033 \times {0.45}\ moles$

Moles of TPPCl = 0.01485 moles

Molar mass of TPPCl = 342.39 g/mol

The formula for the calculation of moles is shown below:

$moles = \frac{Mass\ taken}{Molar\ mass}$

Thus,

$0.01485\ g= \frac{Mass}{342.39\ g/mol}$

Mass of TPPCl = 5.0845 g

Also,

TPPCl is 94.0 % pure.

It means that 94.0 g is present in 100 g of powder

5.0845 g is present in 5.41 g of the powder.

<u>Answer - 5.41 g</u>

5 0

3 years ago

It the mass of a material is 46 grams and the volume of the material is 8 cm ^3 What would the density of the material to be

Nat2105 [25]

5.75 Grams per cm^3

You do mass divided by volume

3 0

3 years ago

......... ..plz hep<br>???? <br>

likoan [24]

I’m positive it’s gonna be c

6 0

3 years ago

This patient has a bone density of 820mg/cm3. What is the volume of a 25g sample?

mamaluj [8]

<u>Answer:</u> The volume of bone for given sample is $30.49cm^3$

<u>Explanation:</u>

To calculate volume of a substance, we use the equation:

$\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}$

Density of bone = $820mg/cm^3=0.82g/cm^3$ (Conversion factor: 1 g = 1000 mg)

Mass of bone = 25 g

Putting values in above equation, we get:

$0.82g/cm^3=\frac{25g}{\text{Volume of bone}}\\\\\text{Volume of bone}=30.49cm^3$

Hence, the volume of bone for given sample is $30.49cm^3$

3 0

3 years ago

The change in entropy, Δ S ∘ rxn , is related to the the change in the number of moles of gas molecules, Δ n gas . Determine the

rewona [7]

Answer:

The entropy decreases.

Explanation:

The change in the standard entropy of a reaction (ΔS°rxn) is related to the change in the number of gaseous moles (Δngas), where

Δngas = n(gaseous products) - n(gaseous reactants)

If Δngas > 0, the entropy increases
If Δngas < 0, the entropy decreases.
If Δngas = 0, there is little or no change in the entropy.

Let's consider the following reaction.

2 H₂(g) + O₂(g) ⟶ 2 H₂O(l)

Δngas = 0 - 3 = -3, so the entropy decreases.

8 0

3 years ago