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3 years ago

If a gas furnace releases 420 kcal of heat energy, what is the energy in kilojoules? (1 cal = 4.184 J)

1 answer:

8 0

Answer:
The furnace releases 1757280 J

Explanation:
We will do the conversion on two steps:
1- convert the kcal to cal
2- convert the cal to J

Step 1: converting kcal to cal
1 kcal is equivalent to 1000 cal. Therefore:
420 kcal is equivalent to 420*1000 = 420000 cal

Step 2: converting cal to J
We are given that:
<span>1 cal = 4.184 J
</span>Therefore:
420000 cal is equivalent to 420000 * 4.184 = 1757280 J

Hope this helps :)

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In the titration of 50. 0 mL of 0. 400 M HCOOH with 0. 150 M LiOH, how many mL of LiOH are required to reach the equivalence poi

mart [117]

The volume of the 0.15 M LiOH solution required to react with 50 mL of 0.4 M HCOOH to the equivalence point is 133.3 mL

<h3>Balanced equation </h3>

HCOOH + LiOH —> HCOOLi + H₂O

From the balanced equation above,

The mole ratio of the acid, HCOOH (nA) = 1

The mole ratio of the base, LiOH (nB) = 1

<h3>How to determine the volume of LiOH </h3>

Molarity of acid, HCOOH (Ma) = 0.4 M
Volume of acid, HCOOH (Va) = 50 mL
Molarity of base, LiOH (Mb) = 0.15 M

Volume of base, LiOH (Vb) =?

MaVa / MbVb = nA / nB

(0.4 × 50) / (0.15 × Vb) = 1

20 / (0.15 × Vb) = 1

Cross multiply

0.15 × Vb = 20

Divide both side by 0.15

Vb = 20 / 0.15

Vb = 133.3 mL

Thus, the volume of the LiOH solution needed is 133.3 mL

Learn more about titration:

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8 0

2 years ago

2. HOW MUCH HEAT IS REQUIRED TO BE RELEASED WHEN

jarptica [38.1K]

Answer: -112200J

Explanation:

The amount of heat (Q) released from an heated substance depends on its Mass (M), specific heat capacity (C) and change in temperature (Φ)

Thus, Q = MCΦ

Since,

Q = ?

Mass of water vapour = 30.0g

C = 187 J/ G°C

Φ = (Final temperature - Initial temperature)

= 100°C - 120°C = -20°C

Then apply the formula, Q = MCΦ

Q = 30.0g x 187 J/ G°C x -20°C

Q = -112200J (The negative sign does indicates that heat was released to the surroundings)

Thus, -112200 joules of heat is released when cooling the superheated vapour.

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3 years ago

12.23 g of ammonia (NH3) are dissolved in enough water to make 560.0 mL of solution. How many moles of NH3 are added to the wate

Karolina [17]

Answer:

0.719 moles of NH₃

Explanation:

Molar mass of ammonia 17 g/mol

Mass of amonia = 12.23 g

Mass / Molar mass = Moles

12.23 g / 17 g/mol = 0.719 moles

4 0

3 years ago

Which property do metalloids share with non metals?

mamaluj [8]

Answer:

their ability to conduct heat and electricity.

Explanation:

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3 years ago

If 42 grams of carbon and 52 grams of oxygen are used, how many grams of CO2 will be produced (Hint: find the

zavuch27 [327]

Answer:

71.5g

Explanation:

The reaction equation is given as:

C + O₂ → CO₂

Mass of C = 42g

Mass of O₂ = 52g

Unknown:

Mass of CO₂ produced = ?

Solution

Now to solve this problem, we have to find limiting reactant which is the one given in short supply in this reaction.

The extent of the reaction is controlled by this reactant.

Find the number of moles of the given species;

Number of moles = $\frac{mass}{molar mass}$

Number of moles of C = $\frac{42}{12}$ = 3.5mol

Number of moles of O₂ = $\frac{52}{32}$ = 1.63mol

Now;

From the balanced reaction equation;

1 mole of C reacted with 1 mole of O₂

We see that C is in excess and O₂ is the limiting reactant.

1 mole of O₂ will produce 1 mole of CO₂

So; 1.63mole of O₂ will produce 1.63 mole of CO₂

Mass of CO₂ = number of moles x molar mass

Molar mass of CO₂ = 44g/mol

Mass of CO₂ = 1.63 x 44 = 71.5g

8 0

2 years ago