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Strike441 [17]
3 years ago
11

Henry mixed salt and water together in a cup until he observed a clear solution. He measured the mass of the solution. Then he p

laced the cup outside for several sunny days during the summer. After a week, he observed that only solid salt remained in the cup and the mass had decreased. Henry concluded that a physical and chemical change occurred in this investigation.
Which statements correctly defend or dispute his conclusion?

1- He is correct. Dissolving salt in water is a physical change, but evaporating the water is a chemical change. Formation of a solid is evidence that a chemical change occurred.
He is correct. Evaporation is a physical change, but dissolving salt in water is a chemical change. The change in mass is evidence that a chemical change occurred.


2- He is incorrect. Dissolving salt in water and evaporation of the water are both physical changes. The reappearance of salt is evidence that the change was reversible by a physical change, so it could not be a chemical change.


3- He is incorrect. Dissolving salt in water and evaporation of the water are both chemical changes. The reappearance of salt is evidence that the change was reversible by a chemical change, so it could not be a physical change.

Chemistry
3 answers:
Keith_Richards [23]3 years ago
7 0

Answer:  

He is correct. Evaporation is a physical change, but dissolving salt in water is a chemical change. The change in mass is evidence that a chemical change occurred.

Explanation:

Dissolving Salt in water is a<u> Chemical Change, </u>Because the Salt arrangement is different in solid state than dissolved in water. As we can see in the image below, once the Salt is dissolved, it is separated into its ions, Na+ and Cl-

Now, The evaporation process is a <u>physical change,</u> because the water doesn´t change its configuration H20 and it only changes its form, as we can see in the image below.

Svet_ta [14]3 years ago
5 0
Statement 2 is correct.
solids moving into solution is a physical change as the core structure of the molecules remain the same. evaporation of water and crystallization of salt are both physical changes as well.
The water does not change it's H2O chemical makeup because salt was dissolved into it.
datboi2 years ago
0 0

He is correct. Evaporation is a physical change, but dissolving salt in water is a chemical change. The change in mass is evidence that a chemical change occurred.

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What amount (moles) of compound is present in 1.00 g of each of the compounds in Exercise 54?
Anika [276]

Answer:

1. Caffeine, C₈H₁₀N₄O₂

Amount = 1.00/194 = 0.00515 moles

2. Ethanol, C₂H₅OH

Amount = 0.0217 moles

3. Dry Ice, CO₂

amount = 0.0227 moles

<em>Note: The question is incomplete. The compound are as follows:</em>

<em> 1. Caffeine, C₈H₁₀N₄O₂;</em>

<em>2. Ethanol, C₂H₅OH;</em>

<em>3. Dry Ice, CO₂</em>

Explanation:

Amount (moles) = mass in grams /molar mass in grams per mole

1. Caffeine, C₈H₁₀N₄O₂

molar mass of caffeine = 194 g/mol

Amount = 1.00 g/194 g/mol = 0.00515 moles

2. Ethanol, C₂H₅OH

molar mass of ethanol = 46 g/mol

Amount = 1.00 g/46 g/mol = 0.0217 moles

3. Dry Ice, CO₂

molar mass of dry ice = 44 g/mol

amount = 1.00 g/44 g/mol = 0.0227 moles

5 0
3 years ago
. Give an example of a salt that is less soluble when the temperature increases
77julia77 [94]

Answer:

cerium (iii) sulfate is less soluble

6 0
2 years ago
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Compare and contrast absolute and relative dating
svet-max [94.6K]
There is no question
7 0
2 years ago
Dry ice is solid carbon dioxide. Instead of melting, solid carbon dioxide sublimes according to the following equation: CO2(s)→C
GREYUIT [131]

Answer:

m=8.79kg

Explanation:

First of all we need to calculate the heat that the water in the cooler is able to release:

Q=\rho * V*Cp*\Delta T

Where:

  • Cp is the mass heat capacity of water
  • V is the volume
  • \rho is the density

Q=1 g/cm^3 *15000 cm^3*4.184 \frac{J}{g*^{\circ}C}*(10-90)^{\circ}C

Q=-5020800 J=-5020.8 kJ

To calculate the mass of CO2 that sublimes:

-Q=\Delta H_{sub}*m

Knowing that the enthalpy of sublimation for the CO2 is: \Delta H_{sub}=571 kJ/kg

5020.8 kJ=571 kJ/kg*m

m=\frac{5020.8 kJ}{571 kJ/kg}=8.79kg

6 0
3 years ago
The rate law for 2NO(g) + O₂(g) → 2NO₂(g) is rate = is rate k[NO]²[O₂]. is rateIn addition to the mechanism in the text (p. 709)
KonstantinChe [14]

The rate law depicts the effect of concentration on reaction rate. Second mechanism 2NO(g) ⇄ N₂O₂(g) [fast], N₂O₂(g) + O₂(g) → 2NO₂(g) [slow] is most reasonable. Thus, option b is correct.

<h3>What is rate law?</h3>

Rate law and equation give the rate at which the reaction takes place under the influence of the concentration of the reactants. The balanced chemical reaction is given as,

2NO(g) + O₂(g) → 2NO₂(g)

The rate of the equation is given as,

rate = k [NO]² [O₂]  

In a multi-step chemical reaction, the slowest step is the rate-determining step. The second mechanism is given as,

2NO (g) → N₂O₂ (g) [fast]

N₂O₂(g) +O₂(g) → 2NO₂ (g) [slow]

Rate is given as,

rate = k [N₂O₂] [O₂]

Therefore, option b. the second mechanism is the most reasonable.

Learn more about rate law, here:

brainly.com/question/14779101

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5 0
2 years ago
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