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3 years ago

How many joules are required to change 40 grams of water to steam at the boiling point?

Chemistry

1 answer:

TEA [102]3 years ago

3 0

Answer:

2260 J

Explanation:

For water at its boiling point of 100 ºC, the heat of vaporization is 2260 J g-1. This means that to convert 1 g of water at 100 ºC to 1 g of steam at 100 ºC, 2260 J of heat must be absorbed by the water.

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When a sample of ca(s) loses 1 mole of electrons in a reaction with a sample of o2(g) the oxygen?

Stolb23 [73]

The reaction involved in present case is:

Net Reaction: Ca + 1/2 O2 → CaO. ..................(1)

In terms of oxidation and reduction, the reaction can be shown at

Oxidation: Ca → Ca2+ + 2e- .................(2)
Reduction: 1/2O2 + 2e- → O2-...................(3)

From, reaction 1 it can be seen that 1 mol of Ca reacts with 1/2 mol of O2 to form 1 mol of CaO.

From, reaction 2 it can be seen that 1 mol of Ca, generates 2 mol of e-.

Thus, when 1/2 mol of Ca is used in reaction, it will lose 1 mol of electrons.

6 0

3 years ago

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As a technician in a large pharmaceutical research firm, you need to produce 250. mL of a potassium dihydrogen phosphate buffer

Reika [66]

Answer:

We will need 147.772 mL of KH2PO4 to make this solution

Explanation:

For this case we can give the following equation:

H2PO4 - ⇄ H+ + HPO42-

With following pH- equation:

pH = pKa + log [HPO42-]/[H2PO4-]

7.05 = 7.21 + log [HPO42-]/[H2PO4-]

-0.16 = log [HPO42-]/[H2PO4-]

10^-0.16 = [HPO42-]/[H2PO4-]

0.6918 = [HPO42-]/[H2PO4-]

Let's say the volume of HPO42-= x then the volume of H2PO4- will be 250 mL - x

Since both have a concentration of 1M = 1 mol /L

If we plug this in the equation 0.6918 = [HPO42-]/[H2PO4-]

0.6918 = x / (250 - x)

0.6918*250 - 0.6918x = x

172.95 = 1.6918x

x = 102.228 mL

The volume of HPO42- = 102.228 mL

Then the volume of H2PO4- = 250 - 102.228 = 147.772 mL

To control this we can plug this in the pH equation

7.05 = 7.21 + log [HPO42-]/[H2PO4-]

7.05= 7.21 + log (102.228 / 147.772) = 7.05

We will need 147.772 mL of KH2PO4 to make this solution

3 0

3 years ago

The amount of kinetic energy an object has depends on its:

UkoKoshka [18]

Answer:

the 4th one

Explanation:

kinitc energy formula is1/2mv^

there is mass ,and velocity (speed)

I hope it help

3 0

2 years ago

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How many bonds and lone pairs are in the molecule SIH4?

lesantik [10]

Answer:

there are no valence electrons left over, so the molecule has four bond pairs and no lone pairs.

Explanation:

6 0

3 years ago

All atomic nuclei, except those of ordinary hydrogen, contain neutrons. <br> a. True<br> b. False

ozzi

This would be false

4 0

3 years ago

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