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alisha [4.7K]
3 years ago
15

Can yall help me with this one, thanks!

Chemistry
1 answer:
Lynna [10]3 years ago
5 0

Answer:

Element   atom    molar mass     Total        % composition

Na               1            23                    40             57.5 %

O                 1            16                     40              40%

H                1               1                      40              2.5 %

The given compound is NaOH.

Na : number of atom= 1

Molar mass= 23 g/mol

Total mass of NaOH = 40 g/mol

% composition by mass = \frac{\text {mass of atom}}{\text {Total mass}}\times 100=\frac{23}{40}\times 100=57.5\%

O : number of atom= 1

Molar mass= 16 g/mol

Total mass of NaOH = 40 g/mol

% composition by mass = \frac{\text {mass of atom}}{\text {Total mass}}\times 100=\frac{16}{40}\times 100=40\%

H : number of atom= 1

Molar mass= 1 g/mol

Total mass of NaOH = 40 g/mol

% composition by mass = \frac{\text {mass of atom}}{\text {Total mass}}\times 100=\frac{1}{40}\times 100=2.5\%

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The combustion reaction described in part (b) occurred in a closed room containing 5.56 10g of air
ziro4ka [17]

Answer:

Explanation:

Combustion reaction is given below,

C₂H₅OH(l) + 3O₂(g) ⇒ 2CO₂(g) + 3H₂O(g)

Provided that such a combustion has a normal enthalpy,

ΔH°rxn = -1270 kJ/mol

That would be 1 mol reacting to release of ethanol,

⇒ -1270 kJ of heat

Now,

0.383 Ethanol mol responds to release or unlock,

(c) Determine the final temperature of the air in the room after the combustion.

Given that :

specific heat c = 1.005 J/(g. °C)

m = 5.56 ×10⁴ g

Using the relation:

q = mcΔT

- 486.34 =  5.56 ×10⁴  × 1.005 × ΔT

ΔT= (486.34 × 1000 )/5.56×10⁴  × 1.005

ΔT= 836.88 °C

ΔT= T₂ - T₁

T₂ =  ΔT +  T₁

T₂ = 836.88 °C + 21.7°C

T₂ = 858.58 °C

Therefore, the final temperature of the air in the room after combustion is 858.58 °C

4 0
3 years ago
Calculate the freezing point of the solution containing 0.105 m k2s. calculate the boiling point of the solution above. -g
Licemer1 [7]
Quantity of K2S m = 0.105 m 
Number of ions i = 2(K) + 1(S) = 3
 Freezing point depression constant of water Kf = 1.86 
delta T = i x m x Kf = 3 x 0.105 x 1.86 = 0.586
 Freezing point = 0 - 0.586 = 0.586 C
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3 years ago
Read 2 more answers
In the titration of HCl with NaOH, the equivalence point is determined
kondaur [170]

Answer:

In the titration of HCl with NaOH, the equivalence point is determined from the point where the phenolphthalein turns pink and then remains pink on swirling.

Explanation:

The equivalence point is the point at which exactly enough titrant (NaOH) has been added to react with all of the analyte (HCl). Up to the equivalence point, the solution will be acidic because excess HCl remains in the flask.

Phenolphtalein is chosen because it changes color in a pH range between 8.3 – 10. Phenolphthalein is naturally colorless but turns pink in alkaline solutions. It remains colorless throughout the range of acidic pH levels, but it begins to turn pink at a pH level of 8.3 and continues to a bright purple in stronger alkalines.

It will appear pink in basic solutions and clear in acidic solutions.

The more NaOH added, the more pink it will be. (Until pH≈ 10)

In strongly basic solutions, phenolphthalein is converted to its In(OH)3− form, and its pink color undergoes a rather slow fading reaction and becomes completely colorless above 13.0 pH

a. from the point where the pink phenolphthalein turns colorless and then remains colorless on swirling.

⇒ the more colorless it turns, the more acid the solution. (More HCl than NaOH)

b. from the point where the phenolphthalein turns pink and then remains pink on swirling.

The equivalence point is the point where phenolphtalein turns pink and remains pink ( Between ph 8.3 and 10). (

Although, when there is hydrogen ions are in excess, the solution remains colorless. This begins slowely after ph= 10 and can be noticed around ph = 12-13

c. from the point where the pink phenolphthalein first turns colorless and then the pink reappears on swirling.

Phenolphthalein is colorless in acid solutions (HCl), and will only turn pink when adding a base like NaOH

d. from the point where the colorless phenolphthalein first turns pink and then disappears on swirling

Phenolphthalein is colorless in acid or neutral solutions. Once adding NaOH, the solution will turn pink. The point where the solution turns pink, and stays pink after swirling is called the equivalence point. When the pink color disappears on swirling, it means it's close to the equivalence point but not yet.

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Which of the following best describes the force causing a rocket to lift off?
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B gravitational force

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grandymaker [24]

The component of the dri reflects the requirement of a nutrient for 50 percent of healthy americans and canadians in a specific life stage and gender is Estimated Average Requirement (EAR).

What is EAR?

A daily food intake number known as the Estimated Average Requirement (EAR) is one that is thought to satisfy the needs of 50% of healthy persons in a given life stage and gender group.

Based on a review of the scientific literature, the estimated average requirements (EAR) are predicted to meet the needs of 50% of the population in that age range.

It serves as the foundation for the creation of RDAs and is employed to assess the sufficiency of nutritional consumption for a given population.

To learn more about EAR click the given link

brainly.com/question/14449512

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