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denis23 [38]
2 years ago
8

Which is the most important question for deciding if a chemical reaction has occurred?

Chemistry
2 answers:
777dan777 [17]2 years ago
7 0

Answer:

all these are physical properties except release of heat so it's probably heat energy given off

navik [9.2K]2 years ago
4 0

Answer:Was any heat energy given off?

Explanation:

A chemical reaction may exothermic (heat is given off) or endothermic (heat is absorbed). Size, density or texture of the substance are strictly physical properties which cannot confirm that a chemical reaction has transpired in the sample. The evolution of heat ultimately confirms that a chemical process has taken place.

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How many molecules are there in 9.34 grams of LiCL
julia-pushkina [17]
Assuming the question refers to LiCl (Lithium chloride) which has a molecular weight 42.39.  <span>Avogadro's constant states there are 6.022 141 79x1023 molecules per mole  </span><span>9.34 g LiCl is 9.34/42.39 mole (0.220 mole) LiCl </span>
<span>The number of molecules is therefore 6.022 141 79x1023x 0.220 =1.326x1023 molecules</span>
7 0
1 year ago
Acetaldehyde decomposes at 750 K: CH3CHO → CO + CH4. The reaction is first order in acetaldehyde and the half-life of the reacti
Degger [83]

Answer:

k = 1.3 x 10⁻³ s⁻¹

Explanation:

For a first order reaction the integrated rate law is

Ln [A]t/[A]₀ = - kt

where [A] are the concentrations of acetaldehyde in this case, t is the time and k is the rate constant.

We are given the half life for the concentration of acetaldehyde to fall to one half its original value, thus

Ln [A]t/[A]₀ = Ln 1/2[A]₀/[A]₀= Ln 1/2 = - kt

- 0.693 = - k(530s) ⇒ k = 1.3 x 10⁻³ s⁻¹

4 0
1 year ago
Calculate the number of chloride ions in 6.8 g of zinc chloride
Bumek [7]

Answer:

The correct answer is 0.300 * 10^23 ions.

Explanation:

Based on the given question, there is a need to find the number of chloride ions in the mentioned 6.8 grams of zinc chloride compound.  

The moles of zinc chloride (ZnCl2) is,  

= mass of zinc + 2 mass of chlorine

= 65.38 + 2 (35.45)

=65.38 + 70.90

= 136.28 grams (The molecular mass of zinc is 65.38 and the molecular mass of chlorine is 35.45)

Thus, 136.28 g of ZnCl2 contains 70.90 grams of chlorine

Therefore, 6.8 grams of ZnCl2 will comprise = (70.90/136.28) * 6.8

= 3.537 g of chlorine

70.90 g of Cl comprise 6.022*10^23 chlorine, thus, 3.537 g of Cl will comprise (6.022*10^23/70.90) * 3.537

= 0.300 * 10^23 ions of chlorine.  

3 0
2 years ago
Among these processes, which is the slowest chemical reaction?
user100 [1]
After some thinking I have come to the conclusion that the answer is C.
8 0
2 years ago
Read 2 more answers
Draw the Lewis structure (including resonance structures) for diazomethane (CH2N2)(CH2N2). For each resonance structure, assign
Tanya [424]

Answer : The Lewis-dot structure and resonating structure of CH_2N_2 is shown below.

Explanation :

Resonance structure : Resonance structure is an alternating method or way of drawing a Lewis-dot structure for a compound.

Resonance structure is defined as any of two or more possible structures of the compound. These structures have the identical geometry but have different arrangements of the paired electrons. Thus, we can say that the resonating structure are just the way of representing the same molecule.

First we have to determine the Lewis-dot structure of CH_2N_2.

Lewis-dot structure : It shows the bonding between the atoms of a molecule and it also shows the unpaired electrons present in the molecule.

In the Lewis-dot structure the valance electrons are shown by 'dot'.

The given molecule is, CH_2N_2

As we know that carbon has '4' valence electrons, nitrogen has '5' valence electrons and hydrogen has '1' valence electrons.

Therefore, the total number of valence electrons in CH_2N_2 = 4 + 2(1) + 2(5) = 16

Now we have to determine the formal charge for each atom.

Formula for formal charge :

\text{Formal charge}=\text{Valence electrons}-\text{Non-bonding electrons}-\frac{\text{Bonding electrons}}{2}

For structure 1 :

\text{Formal charge on H}=1-0-\frac{2}{2}=0

\text{Formal charge on H}=1-0-\frac{2}{2}=0

\text{Formal charge on C}=4-2-\frac{6}{2}=-1

For structure 2 :

\text{Formal charge on H}=1-0-\frac{2}{2}=0

\text{Formal charge on H}=1-0-\frac{2}{2}=0

\text{Formal charge on C}=4-0-\frac{8}{2}=0

8 0
2 years ago
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