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2 years ago

George wishes to increase the percent of acid in 50 ml of a 15% acid solution to 25% acid, how much pure acid must be added?

Chemistry

1 answer:

AleksandrR [38]2 years ago

4 0

Answer:

$\approx 6.667ml$

Explanation:

Let $x$ be the quantity of pure acid that you must add, and $y$ the total quantity of acid in the solution final solution. Then when you add x to the solution the 25% of it will be $y$ :

$y=.25(50+x)$

And $y$ is also equal to 15% of the solution of 50ml plus $x$ .

$y=.15(50)+x$

Equalize these two equations to form a new without y and solve:

$.25(50+x)=.15(50)+x\\12.5+0.25x=7.5+x\\12.5-7.5=x-0.25x\\5=0.75x\\x=5/0.75\\x=6\frac{2}{3}\approx 6.667ml$

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What mass of powdered drink mix is needed to make a 0.5 M solution of 100 mL?

Maru [420]

Answer:

There is 17,114825 g of powdered drink mix needed

Explanation:

Step 1 : Calculate moles

As given, the concentration of the drink is 0.5 M, this means 0.5 mol / L

Since the volume is 100mL, we have to convert the concentration,

⇒0.5 / 1 = x /0.1 ⇒ 0.5* 0.1 = x = 0.05 M

This means there is 0.05 mol per 100mL

Step 2 : calculate mass of the powdered drink

here we use the formula n (mole) = m(mass) / M (Molar mass)

⇒ since powdered drink mix is usually made of sucrose (C12H22O11) and has a molar mass of 342.2965 g/mol.

0.05 mol = mass / 342.2965 g/mol

To find the mass, we isolate it ⇒0.05 mol * 342.2965 g/mol = 17,114825g

There is 17,114825 g of powdered drink mix needed

3 0

2 years ago

Read 2 more answers

Which of the following statements describe chemical properties?

Y_Kistochka [10]

Answer:

A. Oxygen gas supports combustion.

B. Hydrofluoric acid reacts with glass.

C. Fertilizers help to increase agricultural production.

Explanation:

Chemical properties can only be observed when a chemical change, i.e. a change in the chemical composition, occurs.

On the other hand, physical properties are observed or measured without altering the composition of the substances.

Typical examples of chemical properties are reactivity, flammability, combustion, oxidation states, acidity, among others that require to carry out a chemical reaction to be observed.

Typical examples of physical properties are freezing point, melting point, boiling point, density, solubility, corrosiveness, among others.

Thus, as for the choices you have:

A. Oxygen gas supports combustion: the only way to observe this property is by carrying out a combustion reaction, so this describes a chemical property.

B. Hydrofluoric acid reacts with glass: again, only by letting hydrofluoric acid react with glass this can be observed, so this is another example of a chemical property.

C. Fertilizers help to increase agricultural production: fertilizers are absorbed by the plants and converted by biochemical reactions, so this also describes a chemical property.

D. Water boils below 100°C on top of a mountain: boiling is a change of state, the water is H₂O and continues having the same composition after boiling, so this describes a physical property.

E. Lead is denser than aluminum: density is measured by physical media, measuring mass and volume; so this is a physical property.

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2 years ago

In order for fission reactions to be successful, they must be self-perpetuating, meaning they must be able to keep themselves go

aleksandrvk [35]

Answer:

Option C is correct.

The minimum amount of material that is needed for a fission reaction to keep going is called the critical mass.

Explanation:

Nuclear fission is the term used to describe the breakdown of the nucleus of a parent isotope into daughter nuclei.

Normally, the initial energy supplied for nuclear fission is the energy to initiate the first breakdown of the first set of radioactive isotopes that breakdown. Once that happens, the energy released from the first breakdown is enough to drive further breakdown of numerous isotopas in a manner that leads to more energy generation.

But, for this to be able to be sustained and not fizzle out, a particular amount of radioactive material to undergo nuclear fission must be present. This particular amount is termed 'critical mass'

Hope this Helps!!!

3 0

2 years ago

Freon-11, CCl3F has been commonly used in air conditioners. It has a molar mass of 137.35 g/mol and its enthalpy of vaporization

PilotLPTM [1.2K]

Answer:

180.56 Kilo joules of energy is removed in the form of heat when 1.00 kg of freon-11 is evaporated.

Explanation:

Molar mass of freon-11 = 137.35 g/mol

Enthalpy of vaporization of freon-11= $\Delta H_{vap}=24.8 kJ/mol$

Mass of freon-11 evaporated = 1.00 kg = 1000 g

Moles of freon-11 evaporated = $\frac{1000 g}{137.35 g/mol}=7.2807 mol$

Energy in the form of heat removed when 1.00 kg of freon-11 gets evaporated:

$7.28067 mol\times \Delta H_{vap}=7.2807 mol\times 24.8 kJ/mol$

$=180.56 kJ$

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2 years ago

In a certain city, electricity costs $0.17 per kW·h. What is the annual cost for electricity to power a lamp-post for 5.50 hours

Anon25 [30]

Answer:

(a) = $34.123

(b) = $8.532

Explanation:

Cost of electricity = $0.17 per kW·h

(a) For a 100 watt bulb which is the same as 100/1000 or 0.1 kW, the cost per hour =

0.1 × 0.17 = $0.017/h

and for 5.5 hours = 0.017×5.5 = $0.0935

The annual cost, which is 365 days, we have

Annual cost = $0.0935 × 365 = $34.123

(b) For the energy efficient 25-watt bulb, we have

25/1000 = 0.025kW

Power cost per annum =

0.025kW×$0.17 per kW·h×5.5×365 = $8.532

Total cost of using the energy efficient fluorescent bulb is about $3.49

Total cost of using the energy efficient bulb = $8.532 + $3.49 = $12.02

Total cost of incandescent bulb = $35.02 while total cost of energy efficient bulb is = $12.02

$12.02 <$35.02

Additional cost of fluorescent bulb is justified

8 0

2 years ago