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2 years ago

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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Chlorine gas was first prepared in 1774 by the oxidation of NaCl with MnO2:

irina1246 [14]

Answer:

0.5

Explanation:

2NaCl(s) + 2H2SO4(l) + MnO2(s) → Na2SO4(s) + MnSO4(s) + 2H2O(g) + Cl2(g)

Using ideal gas equation,

PV = nRT

28.7torr

Converting torr to atm,

= 0.0378atm

V = 0.597L

T = 27 °C

= 300 K

a) PV = nRT

(0.0378atm) * (0.597L) = n(0.0821) * (300k)

= 0.000915 mol

moles of water and chlorine = 0.000915 mol

From the above equation, the ratio of water to chlorine = 1 : 2

Therefore, mole of chlorine = 0.000915/2

= 0.000458 mol

mole fraction = moles of specie/moles of all the species present

= 0.000458/0.000915

= 0.5

5 0

2 years ago

In Philip’s French class, the students are learning how to pronounce closed vowels and open vowels. The students are most likely

Sladkaya [172]

Answer:

It sounds like they are studying French phonemes

Explanations:

I just learned this.

7 0

2 years ago

Read 2 more answers

How many molecules are in 3.6 grams of NaCl?

raketka [301]

Answer:

$\boxed{\text{None}}$

Explanation:

There are no molecules in NaCl, because it consists only of ions.

However, we can calculate the number of formula units (FU) of NaCl.

Step 1. Calculate the moles of NaCl

$\text{No. of moles}=\text{3.6 g NaCl}\times \dfrac{\text{1 mol NaCl}}{\text{63.54 g NaCl}} = \text{0.0567 mol NaCl}$

Step 2. Convert moles to formula units

$\text{FU} = \text{0.0567 mol NaCl} \times \dfrac{6.022 \times 10^{23}\text{ FU NaCl}}{\text{1 mol NaCl}}\\\\= 3.4 \times 10^{22} \text{ FU NaCl}$

There are $\boxed{3.4 \times 10^{22} \text{ FU NaCl}}$ in 3.6 g of NaCl.

6 0

2 years ago

Dehydrohalogenation of tert-pentyl bromide at higher temperatures will produce 2-methyl-1-butene as the chief product when

salantis [7]

I'm going to suppose you want the adjusted chemical reaction, using the formulas of the compounds. You can see it in the image attached.

6 0

2 years ago

Draw a sodium formate molecule. The structure has been supplied here for you to copy. To add formal charges, click the button be

Karo-lina-s [1.5K]

The Molecule of Sodium Formate along with Formal Charges (in blue) and lone pair electrons (in red) is attached below.

Sodium Formate is an ionic compound made up of a positive part (Sodium Ion) and a polyatomic anion (Formate).

Nomenclature:

In ionic compounds the positive part is named first. As sodium ion is the positive part hence, it is named first followed by the negative part i.e. formate.

Name of Formate:

Formate ion has been derived from formic acid ( the simplest carboxylic acid). When carboxylic acids looses the acidic proton of -COOH, they are converted into Carboxylate ions.

E.g.

HCOOH (formic acid) → HCOO⁻ (formate) + H⁺

H₃CCOOH (acetic acid) → H₃CCOO⁻ (acetate) + H⁺

Formal Charges:

Formal charges are calculated using following formula,

F.C = [# of Valence e⁻] - [e⁻ in lone pairs + 1/2 # of bonding electrons]

For Oxygen:

F.C = [6] - [6 + 2/2]

F.C = [6] - [6 + 1]

F.C = 6 - 7

F.C = -1

For Sodium:

F.C = [1] - [0 + 0/2]

F.C = [1] - [0]

F.C = 1 - 0

F.C = +1

5 0

2 years ago