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3 years ago

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In a chemical change molecules DO NOT create or break chemical bonds to form a new substance you might be able to observe a chem

ical change if you mix things together and see fire bubbles or a change in color (true or false)

1 answer:

vesna_86 [32]3 years ago

3 0

Answer:

false

Explanation:

You might be interested in

Does pyridine undergo nucleophilic aromatic substitution reactions? If no, why not. If yes, on what position does the substituti

sergij07 [2.7K]

Explanation:

Part a

Pyridine is an aromatic heterocyclic compound and undergoes nucleophilic aromatic substitution reaction at 2 and 4 positions.

This is because, when a nucleophile attack pyridine at 2 and 4 positions, the anoin formed is stabilized. In the anion formed is tabilized by resonance and also negative charge is present at electronegative atom, nitrogen.

If the nucleophile attack at 3 position, the anion formed is not as stable as anions formed when nucleophile attach at 2 and 4 positions. This is because negative charge is not present at the nitrogen atom.

Part b:

Tautomers are structural isomers of each others formed by migration atom within the molecule. Tautomers exist in equilibrium with each other.

Tautomers of 2-Hydroxypyridine and 4-Hydroxypyrine are given in the attachment.

5 0

3 years ago

Suppose that you place exactly 100 bacteria into a flask containing nutrients for the bacteria and that you find the following d

tresset_1 [31]

Answer:

The order of the production of bacteria is 1.

12,787 bacteria will be present after 112 min.

$0.04331 min^{-1}$ is the rate constant for the process.

Explanation:

Rate of formation of bacteria when there 100 bacteria: R

Rate of formation of bacteria when there 200 bacteria: R' =2R

Rate of formation of bacteria is directly proportional to the number of bacteria:

$\frac{R}{R'}=\frac{k[200]^x}{k[400]^x}$

$\frac{R}{2R}=(\frac{200}{400})^x$

x = 1

The order of the production of bacteria is 1.

The half life of the process = $t_{1/2}=16 minutes$

Rate constant of the process = k

For first order process k is only dependent on half life:

$k=\frac{0.693}{t_{1/2}}$

$k=\frac{0.693}{16 min}=0.04331 min^{-1}$

For the first order process the increment numbers is given ;

$N=N_o\times e^{kt}$

Where:

$N_o$ = Initial population

N = Population after time t.

We have ;

$N_o=100$

t = 112 minutes

$N=100\times e^{0.04331 min^{-1}\times 112 min}$

$N = 12,786.82\approx 12,787$

12,787 bacteria will be present after 112 min.

$0.04331 min^{-1}$ is the rate constant for the process.

5 0

3 years ago

A slice of pizza has 500 kcal. If we could burn the pizza and use all the heat to warm a 50-L container of cold water, what woul

gayaneshka [121]

Answer:

10°C

Explanation:

Heat gain by water = Heat lost by the slice of pizza

Thus,

$m_{water}\times C_{water}\times \Delta T=Q$

<u>For water: </u>

Volume = 50.0 L

Density of water= 1 kg/L

So, mass of the water:

$Mass\ of\ water=Density \times {Volume\ of\ water}$

$Mass\ of\ water=1 kg/L \times {50.0\ L}$

Mass of water = 50 kg

Specific heat of water = 1 kcal/kg°C

ΔT = ?

For slice of pizza:

Q = 500 kcal

So,

$50\times 1\times \Delta T=500$

ΔT = 10°C

Increase in temperature = 10°C

3 0

3 years ago

Im in the middle of a chem test and i literally have no clue what is happening

denis23 [38]

Answer:

No question so I'm just taking the points

5 0

3 years ago

Pure ethylene glycol, , is added to 2.00 kg of water in the cooling system of a car. The vapor pressure of the water in the syst

spayn [35]

Answer:

1367.7 g of ethylene glycol was added to the solution

Explanation:

In order to find out the mass of glycol we added, we apply the colligative property of lowering vapor pressure: ΔP = P° . Xm

ΔP = Vapor pressure of pure solvent (P°) - Vapor pressure of solution(P')

525.8 mmHg - 451 mmHg = 451 mmHg . Xm

74.8 mmHg / 451 mmHg = Xm → 0.166 (mole fraction of solute)

Xm = Mole fraction of solute / Moles of solute + Moles of solvent

We can determine the moles of solvent → 2000 g . 1 mol/18 g = 111.1 mol

(Notice we converted the 2kg of water to g)

0.166 = Moles of solute / Moles of solute + 111.1 moles of solvent

0.166 (Moles of solute + 111.1 moles of solvent) = Moles of solute

18.4 moles = Moles of solute - 0.166 moles of solute

18.4 = 0.834 moles of solute → Moles of solute = 18.4/0.834 = 22.06 moles

Let's convert the moles to mass → 62 g/mol . 22.06 mol = 1367.7 g

6 0

3 years ago