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scZoUnD [109]
3 years ago
15

How do you know if a reaction is exothermic?

Chemistry
1 answer:
n200080 [17]3 years ago
3 0
You know if the reaction releases energy or heat.

Info:
<span>An exothermic reaction is a chemical reaction that releases energy by light or heat. It is the opposite of an endothermic reaction. Expressed in a chemical equation: reactants → products + energy.</span>
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1. EXPLAIN the steps required to find the molar mass of NH3 . Also,
Natasha_Volkova [10]

Answer: Molar mass of NH_3 is 17.03 g

Explanation:

Molar mass is defined as the mass in grams of 1 mole of a substance.

S.I Unit of Molar mass is gram per mole and it is represented as g/mol.

It is found by adding the atomic masses of all the elements present.

Atomic Mass of Nitrogen (N) = 14.007 g

Atomic Mass of Hydrogen (H) = 1.008 g

Molar mass of NH_3 = 1(14.007)+3(1.008) g = 17.03 g

7 0
3 years ago
How are the following aspects of a reaction affected by the addition of a catalyst? 1) activation energy of the reverse reaction
snow_tiger [21]

These are four questions and four answers.

Answers:

1) activation energy of the reverse reaction

     b. Decreased

2) Rate of the forward reaction

    a. Increased

3) Rate of the reverse reaction

    a. Increased

4) Activation energy of the forward reaction

    b. decreased

Explanation:

<em>Activarion energy</em> is the energy required by the reactants to form the intermediate transition state and become products.

<em>Catalysts</em> are substances that change the path of the chemical reactions, lowering the activation energy, and thus speeding up the rate of the reactions, since the products can reach the new lower activation energy faster.

The equilibrium reactions are the chemical process in which two reactions, the <em>forward and the reverese reactions</em>, occur simultaneously and at the same rate.  The equlibrium reactions may be represented by:

  • A ⇄ B

Where A → B is the direct or forward reaction, and A ← B is the reverse reaction (note the inversed arrow, from right to left).

For the direct reaction A represents the reactants and B represents the products. On the other hand, B represents the reactants and A represents the reactants of the reverse reaction and A. This, is A is the reactant of the forward reaction and the product of the reverse reaction, while B is the reactant of the reverse reaction and the product of the forward reaction.

Since, <em>the addition of a catalyst</em> lowers the activation energy of the process, the new activation energy is lower for both the forward and the reverse reaction, meaning that:

1. <em>The activation energy of the reverse reaction is decreased</em> (option b. of the first question)

2.<em> The rate of the forward reaction is increased</em> (option a. of the second question)

3. <em>The rate of the reverse reaction is increased</em> (option a. of the third question).

4. <em>Activation energy of the forward reaction is decreased</em> (option b. of the fourth question).

In summary, the addition of a catalyst decreases the activation energy for both forward and reverse reactions, and increases the rate of both forward and reverse reactions.

3 0
3 years ago
Read 2 more answers
A sample of hydrated cobalt (II) chloride has a mass of 5.22 g. After heating, it has a mass of 2.85 g. What is the percent by m
Tom [10]
Answer:
mass of water in hydrate = 2.37 grams

Explanation:
The mass of the hydrated cobalt (III) chloride is the summation of the salt and the water it contains.
This means that:
Total mass of sample = mass of salt + mass of water

Now, we are given that:
total mass of sample = 5.22 grams
mass of salt = mass of sample after heating = 2.85 grams

Substitute to get the mass of water as follows:
5.22 = mass of water in hydrate + 2.85
mass of water in hydrate = 5.22 - 2.85
mass of water in hydrate = 2.37 grams

Hope this helps :)
5 0
3 years ago
Read 2 more answers
What is the energy per mole of photons, in kJ/mol, emitted by an argon ion laser which produces a green beam with a frequency of
Serga [27]

Answer:

Energy per mole of photons = 2.31 × 10^2 KJ/mol

Explanation:

Energy, E = hf;

Where h is Planck's constant = 6.63 ×10^-34, and f is frequency of the photons.

E = 6.63 × 10^-34 × 5.8 × 10^14

E = 3.84 × 10^-22 KiloJoules

I mole of photons contains Avogadro's number of particles, 6.02 × 10^23

Therefore, the energy per mile of photon is 3.84 × 10^-22 KJ × 6.02 × 10^23

Energy per mile of photon = 2.31 × 10^2 KJ/mol

5 0
3 years ago
what volume of hydrogen gas is evolved from a reaction between 0.52 g of Na and water? This gas is collected at 20 C and 745mmHg
guapka [62]
The  volume of  hydrogen  gas  that evolved  is   calculated  as  follows
by  use  of   ideal  gas  equation

that  is  PV = nRT
P=745  mm hg
V= ?
R(gas  constant)= 62.36 L.mm hg/mol.k
T= 20 + 273 = 293 k
n=number  of  moles which is calculated as  follows
find the  moles  of Na  used
= 0.52/23=0.023  moles

write the reacting equation
2Na +2H2O =2NaOH +H2
by  use  of reacting  ratio  between  Na : H2  which  is  2:1  therefore  the mole  of H2 = 0.023/2 =0.0115  moles

by  making  the  volume  the   subject  of  the formula
v=nRT/P
V= (0.0115 x 62.36  x 293) / 745  = 0.283 L


6 0
3 years ago
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