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3 years ago

Pls help because im not smart.-.

Chemistry

2 answers:

FromTheMoon [43]3 years ago

6 0

I think it’s d, hope this helped :)

tangare [24]3 years ago

3 0

Answer:

Im not smart either but im pretty sure its D because its a pie chart so its asking how many and pie charts tell you how much something has

Explanation:

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Where does the LED Light get its energy directly from?

scZoUnD [109]

Answer:

A Light Emitting Diode (LED) is a solid-state semiconductor device that converts electrical energy directly into light. On its most basic level, the semiconductor is comprised of two regions.

Explanation:

In the answer

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3 years ago

Read 2 more answers

In which thermochemical equations would the ΔH be considered a heat of solution? 2NaHCO3(s)→Na2CO3 (s) + H2O (g) + CO2 (g), ΔH =

enyata [817]

Answer:

NH4NO3 (s) --> NH4+ (aq) + NO3- (aq) H = +25.7 kJ/mol

Explanation:

Step 1: Data given

2NaHCO3(s) → Na2CO3 (s) + H2O (g) + CO2 (g) ΔH = –129 kJ

C6H6(s) → C6H6(l) ΔH=+9.87 kJ

NH4NO3(s )→ NH4+(aq) + NO3–(aq) ΔH=+25.7 kJ/mol

2C8H18(l) + 25O2(g) → 16CO2(g) + 18H2O(l) ΔH =–5,471 kJ/mol

Step 2:

2NaHCO3(s) → Na2CO3 (s) + H2O (g) + CO2 (g) H = -129 kJ:

This is the decomposition reaction of NaHCO3.

NaHCO3 will break down and form Na2CO3, H2O and CO2

⇒ the heat here is heat of decomposition

C6H6 (s) --> C6H6 (l), H = +9.87 kJ

In this reaction we'll not form a new product. Benzene will change phase. From its solid form to liquid benzene.

⇒ the heat here is heat of fusion

NH4NO3 (s) --> NH4+ (aq) + NO3- (aq) H = +25.7 kJ/mol

When solid NH4NO3 is dossolved in water. it will dissociate in ammonium ion (NH4+) and nitrate ion (NO3-).

This reaction shows a solid dissolving in water and therefore the H represents the heat of solution.

⇒ The heat here is heat of solution

2C8H18 (l) + 25O2 (g) --> 16CO2 (g) + 18H2O (l), H = -5,471 kJ/mol: this is a combustion reaction

This is the combustion reaction of octane. CO2 and H2O will be produced.

⇒ The heat here is heat of combustion.

8 0

4 years ago

Which element could likely substitute for Si in a solid solution?

yulyashka [42]

Answer:aluminum

Explanation:aluminum is a precious metal which means that it can be changed into a liquid solid or gas

4 0

3 years ago

What volume of air is needed to burn an entire 55-L (approximately 15-gal) tank of gasoline? Assume that the gasoline is pure oc

White raven [17]

Answer:

The volume of air required is 527,686.25L.

Explanation:

When the question says "burn", it refers to a combustion reaction, where a substance (in this case octane) reacts with oxygen to produce carbon dioxide and water.

Step 1: Write a balanced equation

Considering it is a combustion reaction, the balanced equation is:

C₈H₁₈ + 12.5 O₂ ⇄ 8 CO₂ + 9 H₂O

In this step, we start balancing elements that are present only in one compound on each side of the equation, namely, carbon and hydrogen.

To finish, it is important to count that there are the same number of atoms on both sides of the equation. In this case there are 8 atoms of Carbon, 18 atoms of Hydrogen and 25 atoms of Oxygen, so it is balanced.

Step 2: Find out the mass of C₈H₁₈

Since the balanced equation gives us information about the mass of C₈H₁₈ involved in the reaction, we need to find out how many grams we have.

The info we have is:

55 L of gasoline (assuming gasoline to be pure octane).
The density of octane is 0,70 g/cm³

Density relates mass and volume, so we can find out how many grams are represented by 55 L. Since the units used are different, first we need to convert liters into cm³. We use the conversión factor 1 L = 1000 cm³.

$55L.\frac{1000cm^{3} }{1L} =55000cm^{3}$

Since density = mass/volume, we can solve for mass:

$mass = density.volume=0.70\frac{g}{cm^{3} } .55,000cm^{3} =38,500g$

Step 3: Establish the theoretical relationship between the mass of octane and the moles of oxygen.

This relationship comes from the balanced equation.

For octane:

molar mass of C₈H₁₈ = molar mass of C . 8 + molar mass of H . 18 =

12 g/mol . 8 + 1g/mol . 18 = 114 g/mol

According to the balanced equation reacts 1 mol of octane, which means 114 grams of it.

For oxygen:

According to the balanced equation, 12.5 moles of oxygen react.

Then, the relationship is 114 g octane : 12.5 moles of oxygen

Step 4: Use the theorethical relationship to find the moles of oxygen that reacted

We use the mass of octane found in step 2 and apply the proper conversión factor.

$38,500g (octane) . \frac{12.5mol (oxygen)}{114g (octane)} = 4,221.49mol(oxygen)$

Step 5: Find out the volume of oxygen.

We know that 1 mol of any gas at room temperature occupies about 25 L. Then,

$4,221.49mol(oxygen).\frac{25L(oxygen)}{1mol(oxygen)} =105,537.25 L (oxygen)$

Step 6: Look the volume of air that contains such amount of oxygen

Given oxygen represents 20% of air, we can use that relationship to find the volume of air.

$105,537.25L(oxygen).\frac{100L(air)}{20L(oxygen)} =527,686.25L (air)$

4 0

4 years ago

I just need 4-8! Plz hurry!!!!!!!!!!!

RSB [31]

Answer:

4: 90N

5: 7.77777m/s

6: 4

7: 12.5609756098

8: 187.5

Explanation:

8 0

3 years ago