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3 years ago

Which of the changes are chemical changes?

1 answer:

7 0

A chemical change results from a chemical reaction, while a physical change is when matter changes forms but not chemical identity. Examples of chemical changes are burning, cooking, rusting, and rotting. Examples of physical changes are boiling, melting, freezing, and shredding.

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. Calculate the molality of each of the following solutions: (a) 0.710 kg of sodium carbonate (washing soda), Na2CO3, in 10.0 kg

Step2247 [10]

Answer:

a)0.67 molal

b) 5.67 molal

c) 2.82 molal

d) 0.0268 molal

Explanation:

Step 1: Data given

Molality = moles solute / mass solvent

(a) 0.710 kg of sodium carbonate (washing soda), Na2CO3, in 10.0 kg of water—a saturated solution at 0°C

Calculate moles of Na2CO3 = 710 grams / 105.99 g/mol = 6.70 moles

Molality = 6.70 moles / 10 kg = 0.67 molal

(b) 125 g of NH4NO3 in 275 g of water—a mixture used to make an instant ice pack

Calculate moles of NH4NO3 = 125 grams / 80.04 g/mol = 1.56 moles

molality = 1.56 moles / 0.275 kg = 5.67 molal

(c) 25 g of Cl2 in 125 g of dichloromethane, CH2Cl2

Calculate moles Cl2 = 25 grams / 70.9 g/mol= 0.353 moles

Molality = 0.353 moles / 0.125 kg = 2.82 molal

0.372 g of histamine, C5H9N, in 125 g of chloroform, CHCl3

Calculate moles histamine = 0.372 grams / 111.15 g/moles = 0.00335 moles

Calculate molality = 0.00335 moles / 0.125 kg = 0.0268 molal

NOTE: histamine is C5H9N3 not C5H9N

4 0

3 years ago

Calculate the solubility of carbon dioxide in water at an atmospheric pressure of 0.400 atm (a typical value at high altitude).A

Bond [772]

Answer:

The molar solubility of carbon dioxide gas is $4.662\times 10^{-6} M$ .

Explanation:

Henry's law states that the amount of gas dissolved or molar solubility of gas is directly proportional to the partial pressure of the liquid.

To calculate the molar solubility, we use the equation given by Henry's law, which is:

$C_{CO_2}=K_H\times p_{liquid}$

where,

$K_H$ = Henry's constant = $3.50\times 10^{-2}mol/L.atm$

$p_{CO_2}$ = partial pressure of carbonated drink

$p_{CO_2}=p\times \chi_{CO_2}$

where = p = Total pressure = 0.400 atm

$\chi_{CO_2}$ = mole fraction of $CO_2=3.33\times 10^{-4}$

$p_{CO_2}=0.400 atm\times 3.33\times 10^{-4} =0.0001332 atm$

Putting values in above equation, we get:

$C_{CO_2}=3.5\times 10^{-2}mol/L.atm\times 0.0001332 atm\\\\C_{CO_2}=4.662\times 10^{-6} M$

Hence, the molar solubility of carbon dioxide gas is $4.662\times 10^{-6} M$ .

8 0

2 years ago

Is the following a chemical change or a physical change?

spayn [35]

It's a Chemical Change

8 0

3 years ago

Which of the following has the strongest magnetic field?

wariber [46]

Answer:

Jupiter

Explanation:

Please don't report again, That hurt my feelings

8 0

2 years ago

Convert 2.17 x 10 -8 Mg into pg

viktelen [127]

This answer is 24 because 2.17 x 10 -8 is 24 so that would be your answer

4 0

3 years ago