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ArbitrLikvidat [17]
3 years ago
7

How much heat is transferred in the process of completely melting a 1.6kg block of ice starting at -15 degrees Celsius? Is this

process endothermic or exothermic?
Chemistry
1 answer:
mixas84 [53]3 years ago
4 0

Answer:

  • a) Heat = 590 kJ

  • b) Endothermic

Explanation:

<em>Endothermi</em>c processes absorb energy. The final state contains more energy than the initial state.

Since ice absorbs heat energy <em>in the process of completely melting</em> this is an <em>endothermic</em> process.

The process involves two stages: 1) heating the ice up to the melting point, which is 0ºC, and 2) melting the ice.

1. Heating the ice from -15ºC to 0ºC

a) Formula: Q = m×C×ΔT

  • m = 1.6 kg
  • C = 2.108 kJ/kg.ºC (specific heat of ice)
  • ΔT = 15ºC

b) Calculations:

  • Q = m×C×ΔT = 1.6 kg × 2.108 kJ/kg.ºC  × 15ºC = 50.592 kJ

2. Melting the ice at 0ºC

a) Formula:  L = m × ΔHf

  • m = 1.6 kg
  • ΔHf = 334 kJ/kg (latent heat of fussion)

b) Calculations

  •    L = m × ΔHf = 1.6 kg × 334 kJ/kg = 534.40 kJ

<u />

<u>2. Total heat</u>

<u />

  • 50.592 kJ + 534.40 kJ = 584.992 kJ ≈ 590 kJ (rounded to 2 significant figures)
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Find the density of a cube on Earth that weighs 1.5 kg and has a side-length of 10 cm.
Inga [223]

Answer:

1.5g/cm³

Explanation:

density=mass÷volume

mass= 1.5kg (<em>c</em><em>h</em><em>a</em><em>n</em><em>g</em><em>e</em><em> </em><em>i</em><em>n</em><em>t</em><em>o</em><em> </em><em>g</em>) = 1500g

volume of the cube = 10×10×10 = 1000cm³

density= divide 1500g÷1000cm = 1.5g/cm³

<h2>Density= 1.5g/cm³</h2>

YOUR WELCOME!

4 0
3 years ago
Choose the thermochemical equation that illustrates ΔH°f for Li2SO4. Choose the thermochemical equation that illustrates ΔH°f fo
Deffense [45]

Answer:

2Li(s) + ⅛S₈(s, rhombic) + 2O₂(g) → Li₂SO₄(s)  

Explanation:

A thermochemical equation must show the formation of 1 mol of a substance from its elements in their most stable state,.

The only equation that meets those conditions is the last one.

A and B are wrong , because they show Li₂SO₄ as a reactant, not a product.

C is wrong because Li⁺ and SO₄²⁻ are not elements.

D is wrong because it shows the formation of 8 mol of Li₂SO₄.

8 0
3 years ago
What is the percentage yield of O2 if 12.3 g of KClO3 (molar mass 123 g) is decomposed to produce 3.2 g of O2 (molar mass 32 g)
My name is Ann [436]

Answer:

The percentage yield of O2 is 66.7%

Explanation:

Reaction for decomposition of potassium chlorate is:

2KClO₃ →  2KCl  +  3O₂

The products are potassium chloride and oxygen.

Let's find out the moles of chlorate.

Mass / Molar mass = Moles

12.3 g / 123 g/mol = 0.1 mol

So ratio is 2:3, 2 moles of chlorate produce 3 mol of oxygen.

Then, 0.1 mol of chlorate may produce (0.1  .3)/ 2 = 0.15 moles

Let's convert the moles of produced oxygen, as to find out the theoretical yield.

0.15 mol . 32 g/ 1mol = 4.8 g

To calculate the percentage yield, the formula is

(Produced Yield / Theoretical yield) . 100 =

(3.2g / 4.8g) . 100 = 66.7 %

8 0
3 years ago
The first chemists, philosophers like, Aristotle were from which country?
qwelly [4]

Answer:

greece

Explanation:

aristole was particularly from stagria, greece. but most early philosophers are from greece

5 0
3 years ago
When you decrease the volume of a gas, what happens to the temperature?
ale4655 [162]

the temperature is decreased

4 0
3 years ago
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