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3 years ago

Please select the best answer and click "submit."

1 answer:

vladimir1956 [14]3 years ago

5 0

When it comes to physical changes like phase changes, there are two types of heat energy: sensible heat and latent heat. Sensible heat is the heat absorbed/released when you heat the substance but it doesn't change phase. An example would be heating lukewarm water. The substance is liquid all throughout. Latent heat, on the other hand, is the heat absorbed/released when there is a phase change. An example would be boiling water, because it changes liquid to vapor.

Hence, for freezing liquid, you use the latent heat, specifically the heat of fusion. The answer should be

2.5 g * (1 mol/18.02 g) * 6.03 kJ/mol = 0.84 kJ/mol

The answer is not in the choices. You only use Hvap if you boil water.

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Which of the following reactions is balanced?

77julia77 [94]

Answer:

B. CaCl₂ + H₂CO₃ → CaCO₃ + 2HC

Explanation:

A balanced reaction has the same number of atoms in the both sides of the reaction. In the options:

A. CaCl₂ + H₂CO₃ → 2CaCO₃ + HCI

In this reaction there is 1 Ca in reactants and 2 in products -The reaction is unbalanced-

There is 1 Ca is both sides, 2Cl, 2H, 1C and 3 Oxygens -The reaction is balanced

C. CaCl₂ + 2H₂CO₃ → CaCO₃ + HCI

There is 1 Ca in both sides but 2Cl in reactants and 1 in Cl -The reaction is unbalanced-

D. 2CaCl₂ + H₂CO₃ →CaCO₃ + HCI

There are 2 Ca in reactants and 1 in Ca -The reaction is unbalanced-

3 0

2 years ago

Lionel places red blood cells in a beaker of pure water, and then he observes their

scZoUnD [109]

Answer:

The red blood cells will burst

Explanation:

When the red blood cells are placed in pure water, they will gain water by osmosis, swell and finally burst due to their weak cell membranes. This process is referred to as hemolysis.

7 0

2 years ago

GivenL C2H2 + 5O2 ------> 4 CO2 + 2H2O

diamong [38]

Answer:

101 L

Explanation:

35.0 g KOH ÷ 56.09 g/mol KOH × (1 mol H2O/ 1 mol KOH) × 18 g/mol H2O = 11.2 g H2O

35.0 g HCl ÷ 36.45 g/mol HCl × (1 mol H2O/ 1 mol HCl) × 18 g/mol H2O = 17.3 g H2O

35.0 g KOH is the limiting reactant

7 0

2 years ago

How to calculate density (what’s the formula) density=_ divided by _

Sphinxa [80]

Answer:

density equals weigt divided by volume

Explanation:

$density = \frac{m}{v}$

8 0

2 years ago

When 2 moles of Fe(s) react with Cl2(g) to form FeCl3(s) according to the following equation, 799 kJ of energy are evolved.

GenaCL600 [577]

Answer:

1. Exothermic.

2. -1598 kJ.

Explanation:

Hello!

1. In this case, according to the reaction, we can infer that 799 kJ of energy are evolved (given off, released) it means that the enthalpy of reaction is negative as the reactants have more energy than the products; which means this is an exothermic reaction.

2. Here, as we know that the enthalpy of reaction is -799 kJ/mol, we can compute the q-value as shown below, considering the reacted 2 moles of solid iron:

$q=2mol*-799 kJ/mol\\\\q=-1598kJ$

Which means that 1598 kJ of energy are evolved when 2 moles of solid iron react.

Best regards!

4 0

2 years ago