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3 years ago

How many moles are there in 8.50 X 1024 molecules of sodium sulfate, Na2SO3?

1 answer:

7 0

Hello!

To solve this question, we need to use the Avogadro's Number, which is a constant first discovered by Amadeo Avogadro, an Italian scientist. He discovered that in a mole of a substance, there are 6,02*10²³ molecules. Using this relationship, we apply the following conversion factor:

$8,50* 10^{24}molecules* \frac{1 mol Na_2SO_3}{6,02* 10^{23}molecules}=14,12 molesNa_2SO_3$

So, 8,50 * 10²⁴ molecules of Na₂SO₃ represent 14,12 moles of Na₂SO₃

Have a nice day!

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oksano4ka [1.4K]

D. 293
According to Charle’s law, with pressure being constant, an increase in volume will also increase the temperature. 10 degrees Celsius is 283 K, so you would need to find the number greater than 283 K which is 293 K.

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3 years ago

Examples of physical and chemical weathering

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Mass is always conserved in a physical change. Energy may be released or absorbed when a substance changes from one physical state to another. In a chemical change, a chemical reaction yields a completely new substance. A substance's particles are changed during a chemical reaction.

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4 years ago

Caffeine, a stimulant in coffee and tea, has a molar mass of 194.19 g/mol and a mass percentage composition of 49.48% C, 5.19% H

lozanna [386]

Answer : The molecular formula of a caffeine is, $C_8H_{10}N_4O_2$

Solution :

If percentage are given then we are taking total mass is 100 grams.

So, the mass of each element is equal to the percentage given.

Mass of C = 49.48 g

Mass of H = 5.19 g

Mass of N = 28.85 g

Mass of O = 16.48 g

Molar mass of C = 12 g/mole

Molar mass of H = 1 g/mole

Molar mass of N = 14 g/mole

Molar mass of O = 16 g/mole

Step 1 : convert given masses into moles.

Moles of C = $\frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{49.48g}{12g/mole}=4.12moles$

Moles of H = $\frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{5.19g}{1g/mole}=5.19moles$

Moles of N = $\frac{\text{ given mass of N}}{\text{ molar mass of N}}= \frac{28.85g}{14g/mole}=2.06moles$

Moles of O = $\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{16.48g}{16g/mole}=1.03moles$

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For C = $\frac{4.12}{1.03}=4$

For H = $\frac{5.19}{1.03}=5.03\approx 5$

For N = $\frac{2.06}{1.03}=2$

For O = $\frac{1.03}{1.03}=1$

The ratio of C : H : N : O = 4 : 5 : 2 : 1

The mole ratio of the element is represented by subscripts in empirical formula.

The Empirical formula = $C_4H_5N_2O_1=C_4H_5N_2O$

The empirical formula weight = 4(12) + 5(1) + 2(14) + 16 = 97 gram/eq

Now we have to calculate the molecular formula of the compound.

Formula used :

$n=\frac{\text{Molecular formula}}{\text{Empirical formula weight}}$

$n=\frac{194.19}{97}=2$

Molecular formula = $(C_4H_5N_2O)_n=(C_4H_5N_2O)_2=C_8H_{10}N_4O_2$

Therefore, the molecular of the caffeine is, $C_8H_{10}N_4O_2$

5 0

3 years ago

What do angiosperms reproduce with?

SCORPION-xisa [38]

Answer:

Angiosperms are vascular plants. ... Unlike gymnosperms such as conifers and cycads, angiosperm's seeds are found in a flower. Angiosperm eggs are fertilized and develop into a seed in an ovary that is usually in a flower. The flowers of angiosperms have male or female reproductive organs.

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3 years ago

At 25◦C and atmospheric pressure the volume change of mixing of binary liquid mixtures of species 1 and 2 is given by)2545(2121x

lions [1.4K]

The question is incomplete. The complete question is:

At 25◦C and atmospheric pressure the volume change of mixing of binary liquid mixtures of species 1 and 2 is given by the equation:

ΔV = x1x2(45x1 + 25x2)

Where ΔV is in cm3-mol-1. At these conditions, the molar volumes of pure liquid 1 and 2 are V1= 110 and V2= 90 cm3-mol-1. Determine the partial molar volumes 1VE and 2VE in a mixture containing 40 mole percent of specie 1.

Answer:

1VE = 117.92 cm³.mol⁻¹, 2VE = 97.92 cm³.mol⁻¹

Explanation:

In the equation given, x represents the molar fraction of each substance, thus x1 = 0.4 and x2 = 0.6. Because of the mixture, the molar partial volume of each substance will change by a same amount, which will be:

ΔV = 0.4*0.6(45*0.4+ 25*0.6)

ΔV = 7.92 cm³.mol⁻¹

1VE - V1 = 7.92

1VE = 7.92 + 110

1VE = 117.92 cm³.mol⁻¹

2VE - V2 = 7.92

2VE = 7.92 + 90

2VE = 97.92 cm³.mol⁻¹

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3 years ago