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s344n2d4d5 [400]

3 years ago

10

A control in an experiment

1 answer:

ser-zykov [4K]3 years ago

4 0

<h3>Changes with the independent variable...</h3>

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What’s the three states of a substance essential for life on earth

vovikov84 [41]

Liquid, solid and gas.

4 0

3 years ago

What is the percent of nitrogen (N) by mass is a 55.0g sample of Fe(NO3)3? The molar mass of Fe(NO3)3 is 241.86g/mol.

Anna35 [415]

Answer:

22.74%

Explanation:

The mass of nitrogen is 55g

The mass of Fe(NO3)3 is 241.86g/mol

%of nitrogen= mass of nitrogen/molar mass of Fe(NO3)3 ×100

= 55/241.86×100

=5500/241.86

=22.74%

5 0

3 years ago

Aluminum chloride can be formed from its elements:

saul85 [17]

<u>Answer:</u> The $\Deltas H^o_{formation}$ for the reaction is -1406.8 kJ.

<u>Explanation:</u>

Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.

According to this law, the chemical equation is treated as ordinary algebraic expressions and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the intermediate reactions.

The chemical reaction for the formation reaction of $AlCl_3$ is:

$2Al(s)+3Cl_2(g)\rightarrow 2AlCl_3 (s)$ $\Delta H^o_{formation}=?$

The intermediate balanced chemical reaction are:

(1) $HCl(g)\rightarrow HCl(aq.)$ $\Delta H_1=-74.8kJ$ ( × 6)

(2) $H_2(g)+Cl_2(g)\rightarrow 2HCl(g)$ $\Delta H_2=-185kJ$ ( × 3)

(3) $AlCl_3(aq.)\rightarrow AlCl_3(s)$ $\Delta H_3=+323kJ$ ( × 2)

(4) $2Al(s)+6HCl(aq.)\rightarrow 2AlCl_3(aq.)+3H_2(g)$ $\Delta H_4=-1049kJ$

The expression for enthalpy of formation of $AlCl_3$ is,

$\Delta H^o_{formation}=[6\times \Delta H_1]+[3\times \Delta H_2]+[2\times \Delta H_3]+[1\times \Delta H_4]$

Putting values in above equation, we get:

$\Delta H^o_{formation}=[(-74.8\times 6)+(-185\times 3)+(323\times 2)+(-1049\times 1)]=-1406.8kJ$

Hence, the $\Deltas H^o_{formation}$ for the reaction is -1406.8 kJ.

6 0

3 years ago

How many grams are there in a 14.5 moles lithium permanganate

frutty [35]

There are 1825.6 g in a 14.5 moles Lithium permanganate

<h3> Further explanation</h3>

The mole is the number of particles(molecules, atoms, ions) contained in a substance

1 mol = 6.02.10²³ particles

Can be formulated

N=n x No

N = number of particles

n = mol

No = Avogadro's = 6.02.10²³

Moles can also be determined from the amount of substance mass and its molar mass :

$\tt mol=\dfrac{mass}{MW}$

moles of Lithium permanganate = 14.5

Lithium permanganate (LiMnO4) MW=125.9 g/mol, so mass :

$\tt mass=mol\times MW\\\\mass=14.5\times 125.9~g/mol\\\\mass=1825.6~g$

5 0

3 years ago

Which shows the formula for converting from kelvins to degrees Celsius?

Marianna [84]

Answer:

°C = °K - 273.

Explanation:

the 1st and 2d rows belong to F°; the last one is wrong; correct answer is °C=°K-273 only.

For example, 0°C=273°K; 10°C=283°K; 100°C=373°K.

7 0

2 years ago

Read 2 more answers