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Dmitry [639]
3 years ago
5

Which one of the equations below is an exothermic reaction?

Chemistry
1 answer:
Yuri [45]3 years ago
3 0

Answer:

B) CaO(s) + H2O(l) --> Ca(OH)2(aq)

Explanation:

This is the only reaction with a negative enthalpy value. Exothermic reactions have a negative enthalpy.

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2) Which liberates the most energy?
evablogger [386]

Answer: F(g)+e^-\rightarrow F^-(g)

Explanation:

Electron gain enthalpy is defined as energy released on addition of electron to an isolated gaseous atom.  

The amount of energy released will be maximum when the tendency to attract electrons is maximum. As flourine has atomic number of 9 and has electronic configuration of 2,7. It can readily gain 1 electron to attain stable noble gas configuration and hence liberates maximum energy.

F(g)+e^-\rightarrow F^-(g)

4 0
3 years ago
What are two systems that use radio waves
Goshia [24]
Mobile radio communication
Broadcasting
Navigation systems
7 0
3 years ago
The normal freezing point of water is 0.00 ⁰C. What is the freezing point of a solution containing450.0 mg of ethylene glycol (M
anyanavicka [17]

Answer:

Freezing T° of solution = - 8.98°C

Explanation:

We apply Freezing point depression to solve this problem, the colligative property that has this formula:

Freezing T° of pure solvent - Freezing T° of solution = Kf . m

Kf = 1.86°C/m, this is a constant which is unique for each solvent. In this case, we are using water

m = molality (moles of solute / 1kg of solvent)

We convert the mass of solvent from g to kg

1.5 g . 1kg/1000g = 0.0015 kg

We convert the mass of solute, to moles. Firstly we make this conversion, from mg to g → 450mg . 1g/1000mg = 0.450 g

0.450 g. 1mol / 62.07g = 7.25×10⁻³ moles

Molality → 7.25×10⁻³ mol / 0.0015 kg = 4.83 m

- Freezing T° of solution = 1.86°C /m . 4.83 m - Freezing T° of pure solvent

-Freezing T° of solution = 1.86°C /m . 4.83 m - 0°C

Freezing T° of solution = - 8.98°C

8 0
3 years ago
Read 2 more answers
How will you recognize that a single replacement reaction has occured when you combine an active metal with 6m hcl?
frez [133]

A single replacement or displacement reaction occurs when one ingredient in a compound replaces another. Only another metal can replace a less active one; a metal can only displace another metal, and a non-metal can only displace another non-metal.

<h3>Displacement reaction:</h3>

The tendency of the element to lose electrons is what makes it metallic. Due to their bigger sizes and propensity to lose electrons as size, the number of shells, and nuclear force of attraction rise, the most active metals are found on the left side of the periodic table.

The reaction in which the more reactive element displaces the less reactive element is known as the displacement reaction.

When we combine an active metal with HCl, the reaction is as follows:

We are taking sodium, Na which is the most active metal. It will replace H in HCl because it is more reactive than H.

                       2Na + 2HCl → 2NaCl + H₂

Three ways to recognize if a single displacement reaction has taken place:

1. Color change

2. Formation of bubbles (a gas)

3. Formation of a precipitate

Learn more about displacement reaction here:

brainly.com/question/15343606

#SPJ4

8 0
2 years ago
An alkane used as a lubricant contains 25 carbon atoms. How many hydrogen atoms are present in its structure?
nadya68 [22]

Answer:

52

Explanation:

Alkanes are saturated hydrocarbons, that is, they are formed just by carbon and hydrogen atoms bonded through single covalent bonds. The general formula for alkanes is CnH2n+2.

If n = 25 (25 carbon  atoms), 2n + 2 = 2 × 25 + 2 = 52. There are 52 hydrogen atoms in the structure and the alkane has the formula C₂₅H₅₂.

5 0
3 years ago
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