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3 years ago

What are the controlled variables for water of crystallization experiment?

1 answer:

7 0

Given what we know, we can confirm that as with any experiment, the control variable will be the one that through each trial of the experiment, no matter how many times it is performed, stays constant.

<h3>What is a controlled variable?</h3>

A variable that remains constant through an experiment.
They are used to compare results to the normal condition.
They are also used to isolate the changes to one factor at a time and thus know its exact effects on the outcome.
This increases the accuracy of the data and the subsequent conclusion.

Therefore, we can confirm that if a variable stays constant through each phase and trial of an experiment, it is considered to be a controlled variable and is useful in order to increase the accuracy of the conclusion.

To learn more about control variables visit:

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Which process causes earth to lose thermal energy to space?

Andru [333]

Radiation I believe

7 0

3 years ago

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The balanced combustion reaction for C 6 H 6 is 2 C 6 H 6 ( l ) + 15 O 2 ( g ) ⟶ 12 CO 2 ( g ) + 6 H 2 O ( l ) + 6542 kJ If 8.10

Nataly [62]

Answer:

The final temperature of water = 35.2 °C

Explanation:

Step 1: Data given

Mass of C6H6 = 8.100 grams

Mass of water = 5691 grams

Temperature = 21 °C

Step 2: The balanced equation

2C6H6(l) + 15O2(g) ⟶ 12 CO2 (g) + 6H2O (l) + 6542 kJ

Step 3:

Q = m*c*ΔT.

⇒with Q = the heat released during this reaction (this depends on the amount of reactants used)

⇒ with m= the mass of the water

⇒with c = the "specific heat" of water = how much energy it takes to raise the temp of 1g of water by 1°C

⇒with ΔT = the change in the temperature of the water

For every 2 moles of C6H6 consumed, 6542 kJ of heat is released.

Step 4: Calculate moles for 8.100 grams

8.100grams / 78.11 g/mol= 0.1037 mol es

So, according to the equation, the amount of heat released is:

(0.1037 moles / 2 moles)* (6542 kJ) = 339.2 kJ

Step 5: Calculate the final temperature

Q = mcΔT

ΔT = Q / (m*c)

T2- T1 = Q / (m*c)

T2 = [Q / (m*c)] + T1 = [(339.2 kJ) / (5691g)(0.004186 kJ/g°C)] + 21°C = 35.2°C

The final temperature of water = 35.2 °C

8 0

3 years ago

What is the freezing point (°C) of a solution prepared by dissolving 11.3 g of Ca(NO3)2 (formula weight = 164 g/mol) in 115 g of

Citrus2011 [14]

Answer:

freezing point (°C) of the solution = - 3.34° C

Explanation:

From the given information:

The freezing point (°C) of a solution can be prepared by using the formula:

$\Delta T = iK_fm$

where;

i = vant Hoff factor

the vant Hoff factor is the totality of the number of ions in the solution

Since there are 1 calcium ion and 2 nitrate ions present in Ca(NO3)2, the vant Hoff factor = 3

$K_f$ = 1.86 °C/m

m = molality of the solution and it can be determined by using the formula

$molality = \dfrac{mole \ of \ solute }{kg \ of \ solvent }$

which can now be re-written as :

$molality = \dfrac{mole \ of \ Ca(NO_3)_2}{kg \ of \ water}$

$molality = \dfrac{\dfrac{mass \ of \ \ Ca(NO_3)_2}{molar \ mass of \ Ca(NO_3)_2} }{kg \ of \ water}$

$molality = \dfrac{\dfrac{11.3 \ g }{164 \ g/mol} }{0.115 \ kg }$

molality = 0.599 m

∴

The freezing point (°C) of a solution can be prepared by using the formula:

$\Delta T = iK_fm$

$\Delta T =3 \times (1.86 \ ^0C/m) \times (0.599 \ m)$

$\Delta T =3.34^0 \ C$

$\Delta T =$ the freezing point of water - freezing point of the solution

3.34° C = 0° C - freezing point of the solution

freezing point (°C) of the solution = 0° C - 3.34° C

freezing point (°C) of the solution = - 3.34° C

3 0

3 years ago

Which pair of elements can be used to determine the age of a fossil that is over one billion years old?

lakkis [162]

Answer:

Explanation:

There are some radioactive nuclides can be used to measure time on an archeological scale. One is the best example of this is radiocarbon dating. This process is based on the ratio of caebon-14 to carbon-12 in the atmosphere which is relatively constant.

The half time of C-14 5730 years

Carbon-14 is a radioactive nucleus. It has a half-life of 5730 years.

All living tissues like plants and animal absorbed carbon-12 along with carbon-14 with same ratio of caebon-14 to carbon-12 in the atmosphere.

Carbon-14 dating is based on the ratio of carbon-14 to carbon-12 in the atmosphere which is relatively constant

3 0

4 years ago

Read 3 more answers

Help help help !!!!!!

11111nata11111 [884]

Answer:

3. 116.5 V

4. 119.6 V

Explanation:

3. Determination of the voltage.

Resistance (R) = 25 Ω

Current (I) = 4.66 A

Voltage (V) =?

V = IR

V = 4.66 × 25

V = 116.5 V

Thus, the voltage is 116.5 V

4. Determination of the voltage.

Current (I) = 9.80 A

Resistance (R) = 12.2 Ω

Voltage (V) =?

V = IR

V = 9.80 × 12.2

V = 119.6 V

Thus, the voltage is 119.6 V

4 0

3 years ago