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3 years ago

Which statement is true of a chemical change? (Plato)

Chemistry

2 answers:

MrRa [10]3 years ago

6 0

Answer: i think A

Explanation: if i got it right could you mark me as brainliest

OleMash [197]3 years ago

5 0

Answer:

Explanation:

The answer A is the best answer because it contains the most general characteristic of a chemical change.

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2. How much heat is released when 432g of water cools down from 710C to 180C?

nadya68 [22]

The heat released by the water when it cools down by a temperature difference AT

is Q = mC,AT

where

m=432 g is the mass of the water

C, = 4.18J/gºC

is the specific heat capacity of water

AT = 71°C -18°C = 530

is the decrease of temperature of the water

Plugging the numbers into the equation, we find

Q = (4329)(4.18J/9°C)(53°C) = 9.57. 104J

and this is the amount of heat released by the water.

7 0

3 years ago

Looters break a statue into pieces. How do you expect the weathering of pieces of rock to change?

andreyandreev [35.5K]

The statue will weather faster because of more surface area.

5 0

4 years ago

The temparature of boiling water cannot be measured by _______ temparature

katrin [286]

Answer:

Temperature of boiling water cannot be measured by a Clinical thermometer The reason behind this is that the range of clinical thermometer varies between only 35° C to 42° C.

4 0

3 years ago

Read 2 more answers

Name the following ether: OCH2CH3

Lelu [443]

The name of the given ether is ethyl benzyl ether .

<h3>What are ethers?</h3>

Ethers are organic compounds formed when nan oxygen atom is bonded to two alkyl or aryl groups.

Ethers usually have relatively high boiling points as a result of the central oxygen atom. An example of an ether, is ethyl propyl ether

The name of the given ether is ethyl benzyl ether as it has a benzyl and ethyl group attached to the oxygen atom.

In conclusion, ethers are characterized by an oxygen atom bonded to two alkyl or aryl groups.

Learn more about ethers at: brainly.com/question/20772030

#SPJ1

3 0

2 years ago

Determine the pH of the resulting solution if 25 mL of 0.400 M strychnine (C21H22N2O2) is added to 50 mL of 0.200 M HCl? Assume

DIA [1.3K]

Answer:

pH = 4.56

Explanation:

The strychnine reacts with HCl as follows:

C₂₁H₂₂N₂O₂ + HCl ⇄ C₂₁H₂₂N₂O₂H⁺ + Cl⁻

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For strychnine buffer:

pOH = 5.74 + log [C₂₁H₂₂N₂O₂H⁺] / [C₂₁H₂₂N₂O₂]

Initial moles of C₂₁H₂₂N₂O₂ are:

0.025L * (0.400 mol / L) = 0.01 moles C₂₁H₂₂N₂O₂

And of HCl are:

0.05L * (0.200 mol / L) = 0.01 moles HCl

That means after the reaction, you will have just 0.01 moles of C₂₁H₂₂N₂O₂H⁺ in 50mL + 25mL = 0.075L. And molarity is:

[C₂₁H₂₂N₂O₂H⁺] = 0.01 mol / 0.075L = 0.1333M

This conjugate acid, is in equilibrium with water as follows:

C₂₁H₂₂N₂O₂H⁺(aq) + H₂O(l) ⇄ C₂₁H₂₂N₂O₂ + H₃O⁺

<em />

<em>Where Ka = Kw / Kb = 1x10⁻¹⁴ / 1.8x10⁻⁶ = 5.556x10⁻⁹</em>

<em />

Ka is defined as:

Ka = 5.556x10⁻⁹ = [C₂₁H₂₂N₂O₂] [H₃O⁺] / [C₂₁H₂₂N₂O₂H⁺]

In equilibrium, concentrations are:

C₂₁H₂₂N₂O₂ = X

H₃O⁺ = X

C₂₁H₂₂N₂O₂H⁺ = 0.1333M - X

Replacing in Ka expression:

5.556x10⁻⁹ = [X] [X] / [0.1333M - X]

7.39x10⁻¹⁰ - 5.556x10⁻⁹X = X²

7.39x10⁻¹⁰ - 5.556x10⁻⁹X - X² = 0

Solving for X:

X = - 2.72x10⁻⁵M → False solution. There is no negative concentrations

X = 2.72x10⁻⁵M → Right solution.

As H₃O⁺ = X

H₃O⁺ = 2.72x10⁻⁵M

And pH = -log H₃O⁺

4 0

3 years ago