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3 years ago

5. Which of the following has variable compositionA. WaterB. sugarC, soilD. Salt

Chemistry

1 answer:

erica [24]3 years ago

7 0

Answer:

C. Soil

Explanation:

The choice with variable composition is the soil. Soil have many different composition.

Soil is made up of minerals, organic matter , water and soil air.
Soil minerals are derived from weathered bedrock materials that have been broken down into small pieces.
Organic matter is derived from dead and decaying materials from plants and animals.
All these materials combine together to form a soil.

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Calculate the standard reaction enthalpy for the reaction NO2(g) → NO(g) + O(g) given +142.7 kJ/mol for the standard enthalpy of

bulgar [2K]

Answer:

The standard reaction enthalpy for the given reaction is 235.15 kJ/mol.

Explanation:

$O_2(g) \rightarrow \frac{2}{3}O_3(g),\Delta H^o_{1}=142.7 kJ/mol$ ..[1]

$O_2(g) \rightarrow 2 O(g),\Delta H^o_{2}=498.4 kJ/mol$ ..[2]

$NO(g) + O_3(g)\rightarrow NO_2(g) + O_2(g) ,\Delta H^o_{3} = -200 kJ/mol$ ..[3]

$NO_2(g)\rightarrow NO(g) + O(g),\Delta H^o_{4}=?$ ..[4]

Using Hess's law:

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.

2 × [4] = [2]- (3 ) × [1] - (2) × [3]

$2\times \Delta H^o_{4}=\Delta H^o_{2} -3\times \Delta H^o_{1}-2\times \Delta H^o_{3}$

$2\times \Delta H^o_{4}=498.4 kJ/mol-3\times 142.7 kJ/mol-2\times -200 kJ/mol$

$2\times \Delta H^o_{4}=470.3 kJ/mol$

$\Delta H^o_{4}=\frac{470.3 kJ/mol}{2}=235.15 kJ/mol$

The standard reaction enthalpy for the given reaction is 235.15 kJ/mol.

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3 years ago

Write the name for the compound Al₂S₃

Svetlanka [38]

Answer:

Uh Joe stinky?

Explanation:

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3 years ago

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Which of these is an example of physical change

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Answer:

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2 years ago

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P O R F A V O R

ale4655 [162]

Answer:

a. 45×10³ kg

b. 1.25 kg

c. 5443200 s

d. 2.69×10⁻⁴ m/s²

e. 2.57×10⁻⁶N

f. 7.48×10⁻³ m /s²

g. 2.45 Pa

h. 10 m/s

Explanation:

The SI units are: kg, m, s, N, K, A, Pa, J and cd

a. 1 g is the mass for 1 cm³. We convert the m³ to cm³

45 m³. 1×10⁶ cm³ / 1 m³ = 45×10⁶ cm³

By the way, 45×10⁶ cm³ = 45×10⁶ g

We convert the g to kg → 45×10⁶ g . 1 kg / 1000 g = 45×10³ kg

b. As 1 g = 1 cm³, we convert the cm³ to g and then, the g to kg

1250 cm³ = 1250 g → 1250 g . 1kg / 1000 g = 1.25 kg

c. 1 day has 24 hours; 1 hour has 60 minutes; 1 minute has 60 seconds

1 hour has 3600 s. Then 24 h . 3600 s / 1 h = 86400 s

86400 s/d. 63 d = 5443200 s

d. 1 min² = 3600 s²

97 cm / 3600 s² = 0.0269 cm/s² / 100 = 2.69×10⁻⁴ m/s²

e. 927 g.cm / min² / 3600 s² = 0.2575 g.cm/s² → dyn

We need to convert dyn to N

1 dyn = 10⁻⁵N → 0.2575 dyn . 10⁻⁵N / 1dyn = 2.57×10⁻⁶N

f. 1 m/s² = 12960 km/h²

12960 km/h² . 1 m/s² / 97 km/h² = 7.48×10⁻³ m /s²

g. 2500 g/cm² . 1kg / 1000 g = 2.5 kg/cm²

1 Pa = 1.02kg/cm²

2.5 kg/cm² . 1 Pa / 1.02 kg/cm² = 2.45 Pa

h. 1 h = 3600 s

36 km / 3600 s = 0.01 km /s → 0.01 km . 1000 m / 1 km = 10

= 10 m/s

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2 years ago

How many liters of h2 gas, collected over water at an atmospheric pressure of 752 mmhg and a temperature of 21.0°c, can be made

Shalnov [3]

The answer is V = 0.6 L

The explanation:

1- First we will get P (H) :

p (H) = p total - p (H2O)

= 752 mmHg - 18.65 mmHg

= 733 mmHg

= 733 mmHg X (1 atm / 760 atm) = 0.964 atm

2- then when the reaction equation is:

Zn(s)+2HCl(aq) -> H2(g)+ZnCl2(aq)

so, then 1 mole of Zn will produce 1 mole of H2.

so, we need to get first the mole of Zn:

mole Zn = mass / molar mass

= 1.566g / 65.38g/mol

= 0.02395mol

∴ 0.02395 mol of Zn will produce 0.02395 mol of H2

by using the ideal gas equation we can get the volume V :

when :

PV = nRT

when T is the temperature = 21 + 273 = 294 K

and R is the ideal gas constant = 0.0821 L atm /K mol

and n is the number of moles = 0.2395 mol

and P is the pressure = 0.964 atm

so, by substitution:

V = (0.02395 moles H2)(0.0821 L atm / K mole)(294 K) / (0.964 atm)

= 0.6 L

3 0

3 years ago

Read 2 more answers

5. Which of the following has variable compositionA. WaterB. sugarC, soilD. Salt​

5. Which of the following has variable compositionA. WaterB. sugarC, soilD. Salt