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3 years ago

Finish the story given the beginning:

Chemistry

1 answer:

Ugo [173]3 years ago

7 0

evaporation will happen so yes the puddles will go away with the sun after awhile.

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If 4.50 g of (nh4)2so4 is dissolved in enough water to form 250. ml of solution, what is the molarity of the solution?

natima [27]

The molarity of a solution is the number of moles of a substance in one liter of that substance.
The molar mass of ammonium sulfate (NH4)2SO4 is 132.14 grams/mole
Calculate the moles of ammonium sulfate:
(4.50 grams)/(132.14 grams/mole) = 0.0341 moles of ammonium sulfate
convert mL to Liters 250. mL becomes 0.250 liters
Take the number of moles over the number of liters
0.0341 moles / 0.250 liters = 0.136 molar or 0.136M = molarity of the solution

8 0

3 years ago

How much heat is released when 24.8 g of ch4 is burned in excess oxygen gas?

balu736 [363]

The given question is incomplete. The complete question is:

How much heat is produced when 24.8 g of $CH_4$ is burned in excess oxygen gas

Given: $CH _4
+2O_2\rightarrow CO_2+2H_2O$ ΔH= −802 kJ.

Answer: 1243.1 kJ

Explanation:

Heat of combustion is the amount of heat released on complete combustion of 1 mole of substance.

Given :

Amount of heat released on combustion of 1 mole of methane = 802 kJ kJ/mol

According to avogadro's law, 1 mole of every substance occupies 22.4 L at NTP, weighs equal to the molecular mass and contains avogadro's number $6.023\times 10^{23}$ of particles.

1 mole of $CH_4$ weighs = 16 g

Thus we can say:

16 g of $CH_4$ on combustion releases heat = 802 kJ

Thus 24.8 g of $CH_4$ on combustion releases = $\frac{802}{16}\times 24.8=1243.1kJ$

Thus heat released when 24.8 g of methane is burned in excess oxygen gas is 1243.1 kJ

4 0

3 years ago

Which element has a smaller ionic radius than magnesium (Mg)?

barxatty [35]

Answer:

Na has atomic number 11

which is less than magnesium has atomic number 12

ANSWER IS D

Explanation:

aluminum or Al is atomic 13 and Ca or calcium is atomic number 20 and rubidium or Rb is atomic number 37

6 0

3 years ago

Calculate the freezing point (in degrees C) of a solution made by dissolving 7.99 g of anthracene{C14H10} in 79 g of benzene. Th

mario62 [17]

<u>Answer:</u> The freezing point of solution is 2.6°C

<u>Explanation:</u>

To calculate the depression in freezing point, we use the equation:

$\Delta T_f=iK_fm$

Or,

$\Delta T_f=i\times K_f\times \frac{m_{solute}\times 1000}{M_{solute}\times W_{solvent}\text{ in grams}}$

where,

$\Delta T_f$ = $\text{Freezing point of pure solution}-\text{Freezing point of solution}$

Freezing point of pure solution = 5.5°C

i = Vant hoff factor = 1 (For non-electrolytes)

$K_f$ = molal freezing point depression constant = 5.12 K/m = 5.12 °C/m

$m_{solute}$ = Given mass of solute (anthracene) = 7.99 g

$M_{solute}$ = Molar mass of solute (anthracene) = 178.23 g/mol

$W_{solvent}$ = Mass of solvent (benzene) = 79 g

Putting values in above equation, we get:

$5.5-\text{Freezing point of solution}=1\times 5.12^oC/m\times \frac{7.99\times 1000}{178.23g/mol\times 79}\\\\\text{Freezing point of solution}=2.6^oC$

Hence, the freezing point of solution is 2.6°C

8 0

3 years ago

1. Un átomo de volframio (W) tiene 74 protones y 108 neutrones. ¿Cuál es su representación adecuada?

german

Answer:

Iffdldzdosodolzf cvbvxhmnvhihsoszüf

8 0

2 years ago