When a candle burns what changes are observed?

What is the change in internal energy ( ΔU ) of the system if q = –8 kJ and w = –1 kJ for a certain process?

Radda [10]

Answer:

Change in internal energy (ΔU) = -9 KJ

Explanation:

Given:

q = –8 kJ [Heat removed]

w = –1 kJ [Work done]

Find:

Change in internal energy (ΔU)

Computation:

Change in internal energy (ΔU) = q + w

Change in internal energy (ΔU) = -8 KJ + (-1 KJ)

Change in internal energy (ΔU) = -8 KJ - 1 KJ

Change in internal energy (ΔU) = -9 KJ

6 0

3 years ago

Which of these best explains why a paper clip can float on water? A)Water has a very high specific heat.

stiks02 [169]

Answer:

The answer is d. water molecules near the surface produce more buoyant force than water molecules within the liquid

Explanation: Surface tension is defined as the attraction on the water of like particles to one another. Water molecules on a surface undergoes cohesion or the sticking together of one molecule to another of the same material.

3 0

3 years ago

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While working in the chemistry lab, you dissolve 2.5g of sodium hydroxide chips into a beaker containing 50mL of water. As you p

leva [86]

Answer:

Energy was released when the sodium and hydroxide ions formed new bonds with the water.

Explanation:

4 0

3 years ago

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Consider the following reaction.Cr2O3(s) + 3CCl4(l) 2CrCl3(s) + 3COCl2(g). When the green solid is mixed with the colorless liq

Elena L [17]

Answer:

The answer to your question is: letter B

Explanation:

Reaction

Cr2O3(s) + 3CCl4(l) ⇒ 2CrCl3(s) + 3COCl2(g)

From the information given and the reaction, we can conclude that:

Green solid = Cr2O3 (s) "s" means solid

Colorless liquid = CCl4 (l) "l" means liquid and is the other reactant

Purple solid = CrCl3(s) CrCl3 is purple and "s" solid

Then, as a green specks remains it means that the excess reactant is Cr2O3, so, CCl4 is the limiting reactant.

6 0

3 years ago

Using the following equation, 2C2H6 +7O2 -->4CO2 +6H2O, if 2.5g C2H6 react with 170g of O2, how many grams of water will be p

kirill [66]

The mass of water (H₂O) that would be produced is 4.5 g

<h3>Stoichiometry </h3>

From the question, we are to determine the mass of water that would be produced.

From the given balanced chemical equation

2C₂H₆ +7O₂ → 4CO₂ +6H₂O

This means

2 moles of C₂H₆ reacts with 7 moles of O₂ to produce 4 moles of CO₂ and 6 moles of H₂O

Now, we will determine the number of moles of each reactant present

For Ethane (C₂H₆)

Mass = 2.5 g

Molar mass = 30.07 g

Using the formula,

$Number\ of\ moles = \frac{Mass}{Molar\ mass}$

Number of moles of C₂H₆ present = $\frac{2.5}{30.07}$

Number of moles of C₂H₆ present = 0.08314 mole

For Oxygen (O₂)

Mass = 170g

Molar mass = 31.999 g/mol

Number of moles of O₂ present = $\frac{170}{31.999}$

Number of moles of O₂ present = 5.3127 moles

Since

2 moles of C₂H₆ reacts with 7 moles of O₂

Then,

0.08314 mole of C₂H₆ will react with $\frac{7 \times 0.08314 }{2}$

$\frac{7 \times 0.08314 }{2}$ = 0.58198 mole

Therefore,

0.08314 mole of C₂H₆ reacts with 0.58198 mole of O₂ to produce 3 × 0.08314 moles of H₂O

3 × 0.08314 = 0.24942 mole

Thus, the number of moles of water (H₂O) produced is 0.24942 mole

Now, for the mass of water that would be produced,

Using the formula,

Mass = Number of moles × Molar mass

Molar mass of water = 18.015 g/mol

Then,

Mass of water that would be produced = 0.24942 × 18.015

Mass of water that would be produced = 4.4933 g

Mass of water that would be produced ≅ 4.5 g

Hence, the mass of water (H₂O) that would be produced is 4.5 g

Learn more on Stoichiometry here: brainly.com/question/14271082

3 0

2 years ago