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3 years ago

What is the correct name for the compound CaSO4•2H2O?

1 answer:

5 0

CaSO4.2H2O is a white crystal at room temperature. It is soluble in water. Gypsum can be used as a fertilizer.

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when hydrogen atom absorbs a photon, and an electron moves level 1 to level 2, what happens to the energy of the atom?

pychu [463]

Answer:

When an electron is hit by a photon of light, it absorbs the quanta of energy the photon was carrying and moves to a higher energy state. One way of thinking about this higher energy state is to imagine that the electron is now moving faster, (it has just been "hit" by a rapidly moving photon).

Explanation: pls mark brainliest :))

7 0

2 years ago

I NEED HELP PLEASEEEEEE I WILL RATE BRAINLIEST!!!!

MrRa [10]

0.002 moles is the answer

8 0

2 years ago

Student A performed gravimetric analysis for sulfate in her unknown using the same procedures we did . Results of her three tria

soldi70 [24.7K]

Answer:

The answer is Sodium Sulfate = Na2SO4

Explanation:

Molar mass of sulfate = 1 (S) + 4 (O) = 1 (32) + 4 (16) = 32 + 64 = 96

Molar mass of sodium sulfate = 2 (23) + 96 = 46 + 96 = 142

% of Sulfate = (96/142)*100 = 67.6%

Percent mistake in Studen A,

(I) % mistake = (67.6 - 68.6)/67.6 = 1.48

(ii) % mistake = (67.6 - 66.2)/67.6 = 2.07

(iii) % mistake = (67.6 - 67.1)/67.6 = 0.74

For understudy B

(I) % mistake = (67.6 - 66.7)/67.6 = 1.33

(ii) % mistake = (67.6 - 66.6)/67.6 = 1.48

(iii) % mistake = (67.6 - 66.5)/67.6 = 1.63

Sutdent An is some how exact.

Understudy B is exact however not precise.

8 0

3 years ago

How many moles of sodium carbonate are contained by 57.3g of sodium carbonate

Lady_Fox [76]

Answer:

$\boxed {\boxed {\sf 0.541 \ mol \ Na_2CO_3}}$

Explanation:

We are asked to find how many moles of sodium carbonate are in 57.3 grams of the substance.

Carbonate is CO₃ and has an oxidation number of -2. Sodium is Na and has an oxidation number of +1. There must be 2 moles of sodium so the charge of the sodium balances the charge of the carbonate. The formula is Na₂CO₃.

We will convert grams to moles using the molar mass or the mass of 1 mole of a substance. They are found on the Periodic Table as the atomic masses, but the units are grams per mole instead of atomic mass units. Look up the molar masses of the individual elements.

Na: 22.9897693 g/mol
C: 12.011 g/mol
O: 15.999 g/mol

Remember the formula contains subscripts. There are multiple moles of some elements in 1 mole of the compound. We multiply the element's molar mass by the subscript after it, then add everything together.

Na₂ = 22.9897693 * 2= 45.9795386 g/mol
O₃ = 15.999 * 3= 47.997 g/mol
Na₂CO₃= 45.9795386 + 12.011 + 47.997 =105.9875386 g/mol

We will convert using dimensional analysis. Set up a ratio using the molar mass.

$\frac {105.9875386 \ g \ Na_2CO_3}{1 \ mol \ Na_2CO_3}$

We are converting 57.3 grams to moles, so we multiply by this value.

$57.3 \ g \ Na_2CO_3} *\frac {105.9875386 \ g \ Na_2CO_3}{1 \ mol \ Na_2CO_3}$

Flip the ratio so the units of grams of sodium carbonate cancel.

$57.3 \ g \ Na_2CO_3} *\frac {1 \ mol \ Na_2CO_3}{105.9875386 \ g \ Na_2CO_3}$

$57.3 } *\frac {1 \ mol \ Na_2CO_3}{105.9875386 }$

$\frac {57.3 }{105.9875386 } \ mol \ Na_2CO_3$

$0.5406295944 \ mol \ Na_2CO_3$

The original measurement of moles has 3 significant figures, so our answer must have the same. For the number we found that is the thousandth place. The 6 in the ten-thousandth place to the right tells us to round the 0 up to a 1.

$0.541 \ mol \ Na_2CO_3$

There are approximately 0.541 moles of sodium carbonate in 57.3 grams.

6 0

2 years ago

238,2U --> 234Th + 90

stiv31 [10]

Answer:

$\\_{2}^{4} \alpha$

Explanation:

In this question, we wish to find the missing nuclei for the equation:

$\\_{92}^{238} U\rightarrow _{90}^{234} Th + _{Z}^{A} X$

In order to find the missing species, we need to use the charge and mass balance law. That is, the mass should be conserved: the total mass on the left-hand side with respect to the arrow should be equal to the total mass on the right-hand side with respect to the arrow:

$238 = 234 + A$