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3 years ago

17 Which substance can not be broken down by a chemical change?(1) ammonia (3) propanal

Chemistry

2 answers:

lyudmila [28]3 years ago

6 0

Zirconium cannot be broken down by a chemical change, because it is an element. The others are all molecules.

Sindrei [870]3 years ago

5 0

(4) Zirconium

Because it cannot be broken down by chemical change neither a chemical property. It is an element. It consists of only one atom.

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Calculate the number of calories needed to increase the temperature of 50.0 g of copper metal from 21.0 degrees C to 75.0 degree

KonstantinChe [14]

<h3>Answer:</h3>

1031.4 Calories.

<h3>Explanation:</h3>

We are given;

Mass of the copper metal = 50.0 g

Initial temperature = 21.0 °C

Final temperature, = 75°C

Change in temperature = 54°C

Specific heat capacity of copper = 0.382 Cal/g°C

We are required to calculate the amount of heat in calories required to raise the temperature of the copper metal;

Quantity of heat is given by the formula,

Q = Mass × specific heat capacity × change in temperature

= 50.0 g × 0.382 Cal/g°C × 54 °C

= 1031.4 Calories

Thus, the amount of heat energy required is 1031.4 Calories.

4 0

3 years ago

At 20°C the vapor pressure of benzene (C6H6) is 75 torr, and that of toluene (C7H8) is 22 torr. Assume that benzene and toluene

valina [46]

Answer: The mole fraction of benzene will be 0.34 and mole fraction of toluene is 0.66

Explanation:

According to Raoult's law, the vapor pressure of a component at a given temperature is equal to the mole fraction of that component multiplied by the vapor pressure of that component in the pure state.

$p_1=x_1p_1^0$ and $p_2=x_2P_2^0$

where, x = mole fraction in solution

$p^0$ = pressure in the pure state

According to Dalton's law, the total pressure is the sum of individual pressures.

$p_{total}=p_1+p_2\\$ $p_{total}=x_{benzene}p_{benzene}^0+x_{toluene}P_{toluene}^0$

$x_{benzene}=x$ ,

$x_{toluene}=1-x_{benzene}=1-x$ ,

$p_{benzene}^0=75torr$

$p_{toluene}^0=22torr$

$p_{total}=40torr$

$40=x\times 75+(1-x)\times 22$

$x=0.34$

Thus (1-x0 = (1-0.34)=0.66

Thus the mole fraction of benzene will be 0.34 and that of toluene is 0.66

8 0

3 years ago

Determine whether the stopcock should be completely open, partially open, or completely closed for each activity involved with t

densk [106]

Answer:

Close to the calculated endpoint of a titration - <u>Partially open</u>

At the beginning of a titration - <u>Completely open</u>

Filling the buret with titrant - <u>Completely closed</u>

Conditioning the buret with the titrant - <u>Completely closed</u>

Explanation:

'Titration' is depicted as the process under which the concentration of some substances in a solution is determined by adding measured amounts of some other substance until a rection is displayed to be complete.

As per the question, the stopcock would remain completely open when the process of titration starts. After the buret is successfully placed, the titrant is carefully put through the buret in the stopcock which is entirely closed. Thereafter, when the titrant and the buret are conditioned, the stopcock must remain closed for correct results. Then, when the process is near the estimated end-point and the solution begins to turn its color, the stopcock would be slightly open before the reading of the endpoint for adding the drops of titrant for final observation.

3 0

3 years ago

Which of these is a mixture?Oxygen, air, sugar or common salt

Westkost [7]

Air is a mixture of several gasses

3 0

3 years ago

Calculate the ph of a solution having [OH-] = 8.2 x 10 ^-8M

egoroff_w [7]

Answer:

Explanation:

To find the pH we must first find the pOH

The pOH can be found by using the formula

pOH = - log [ {OH}^{-} ]

We have

$pOH = - log(8.2 \times {10}^{ - 8} ) \\ = 7.086186...$

pOH = 7.09

Next we use the equation

pH = 14 - pOH

We have

pH = 14 - 7.09

We have the final answer as

Hope this helps you

8 0

3 years ago