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taurus [48]
3 years ago
14

How does heavy water in a nuclear reactor help to keep the chain reaction going?

Chemistry
1 answer:
yarga [219]3 years ago
4 0
<span>Heavy water acts as a neutron moderator. The neutrons formed by fission come off at high velocity, but U-235 absorbs neutrons much more strongly when they are slowed down, so all so-called thermal reactors use a moderator to slow them down until they achieve the average velocity appropriate to the atoms of the moderator which is at approx 300 deg C in a water reactor. Other moderators can be light water or graphite. Heavy water has the advantage over light water that it absorbs fewer neutrons so natural uranium can be used, whilst light water requires enriched uranium fuel. Graphite in a very pure form is also a good moderator but requires a gas coolant, carbon dioxide has been used in magnox and agr reactors, but there is a time limit on the life of the reactor due to graphite corrosion, and these are now obsolete as far as new builds are concerned. The Soviet RBMK reactors used graphite but with a water coolant inside pressure tubes, but after Chernobyl there will certainly be no more of these built
</span>
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What is an air mass? Where on Earth might you find a hot and dry air mass?
igor_vitrenko [27]
An air mass is a large volume of air in the atmosphere thats mostly uniform in temperature and moisture. Air masses can extend thousands of kilometers across the surface of the Earth, and can reach from ground level to the stratosphere/10 miles into the atmosphere. an air mass over northern Canada is a continental polar air mass and is cold and dry. One that forms over the Indian Ocean is called a maritime tropical air mass and is warm and humid.
6 0
3 years ago
Match each statements with the state of matter it describes?
Len [333]

Answer:

Solid  liquids , plasma gas

Explanation:

It retains its shape regardless of the shape of the container

5 0
2 years ago
1.20 x 10^22 molecules NaOH to gram
Trava [24]

Answer:

\boxed {\boxed {\sf 0.797 \ g \ NaOH}}

Explanation:

<u>1. Convert Molecules to Moles</u>

First, we must convert molecules to moles using Avogadro's Number: 6.022*10²³. This tells us the number of particles in 1 mole of a substance. In this case, the particles are molecules of sodium hydroxide.

\frac {6.022*10^{23} \ molecules \ NaOH} {1 \ mol \ NaOH}}

Multiply by the given number of molecules.

1.20*10^{22} \ molecules \ NaOH *\frac {6.022*10^{23} \ molecules \ NaOH} {1 \ mol \ NaOH}}

Flip the fraction so the molecules cancel out.

1.20*10^{22} \ molecules \ NaOH *\frac {1 \ mol \ NaOH} {6.022*10^{23} \ molecules \ NaOH}}

1.20*10^{22}  *\frac {1 \ mol \ NaOH} {6.022*10^{23}}}

\frac {1.20*10^{22} \ mol \ NaOH} {6.022*10^{23}}}

0.0199269345732 \ mol \ NaOH

<u>2. Convert Moles to Grams</u>

Next, we convert moles to grams using the molar mass.

We must calculate the molar mass using the values on the Periodic Table. Look up each individual element.

  • Na: 22.9897693 g/mol
  • O: 15.999 g/mol
  • H: 1.008 g/mol

Since the formula has no subscripts, we can simply add the molar masses.

  • NaOH: 22.9897693+15.999+1.008=39.9967693 g/mol

Use this as a ratio.

\frac {39.9967693 \ g  \ NaOH }{1 \ mol \ NaOH}

Multiply by the number of moles we calculated.

0.0199269345732 \ mol \ NaOH*\frac {39.9967693 \ g  \ NaOH }{1 \ mol \ NaOH}

The moles of sodium hydroxide cancel.

0.0199269345732 *\frac {39.9967693 \ g  \ NaOH }{1}

0.0199269345732 *39.9967693 \ g  \ NaOH

0.79701300498 \ g \ NaOH

The original measurement of molecules has 3 significant figures, so our answer must have the same. For the number we calculated, that is the thousandth place. The 0 tells us to leave the 7 in the hundredth place.

0.797 \ g \ NaOH

1.20*10²² molecules of sodium hydroxide is approximately 0.797 grams.

4 0
3 years ago
How much heat is required to change 25.0 g of water from solid to liquid at 0 oC? Water: ΔHfus = 334 J/g; ΔHvap= 2260J/g
xxMikexx [17]

Answer:

The heat required to change 25.0 g of water from solid ice to liquid water at 0°C  is 8350 J

Explanation:

The parameters given are

The temperature of the solid water = 0°C

The heat of fusion,   = 334 J/g

The heat of vaporization, = 2260 J/g

Mass of the solid water = 25.0 g

We note that the heat required to change a solid to a liquid is the heat of fusion, from which we have the formula for heat fusion is given as follows;

ΔH =  m ×

Therefore, we have;

ΔH =  25 g × 334 J/g = 8350 J

Which gives the heat required to change 25.0 g of water from solid ice to liquid water at 0°C  as 8350 J.

3 0
3 years ago
Defention of density in your own words
Readme [11.4K]

Answer:

Density is a word we use to describe how much space an object or substance takes up (its volume) in relation to the amount of matter in that object or substance (its mass). Another way to put it is that density is the amount of mass per unit of volume. If an object is heavy and compact, it has a high density.

Explanation:

8 0
3 years ago
Read 2 more answers
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