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3 years ago

During which stage of life is a human most dependent on others?

Chemistry

2 answers:

AfilCa [17]3 years ago

7 0

Erm, I think when they are little. When they are just born.

JulijaS [17]3 years ago

5 0

Answer:

oral stage

(the stage where humans are still babies)

hope this helps!

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When a 0.245-g sample of benzoic acid is combusted in a bomb calorimeter, the temperature rises 1.643 ∘C . When a 0.260-g sample

sveticcg [70]

Answer:

The heat of combustion per moles of caffeine is 4220 kJ/mol

Explanation:

Step 1: Data given

⇒ When benzoic acid sample of 0.245 grams is burned the temperature rise is 1.643 °C

⇒ When 0.260 gram of caffeine is burned, the temperature rise is 1.436 °C

⇒ Heat of combustion of benzoic acid = 26.38 kJ/g

Step 2: Calculate the heat released: for combustion of benzoic acid

0.245 g benzoic acid * 26.38 kJ/g = 6.4631 kJ

Step 3: Calculate the heat capacity of the calorimeter:

c = Q/ΔT

Q = 6.4631 kJ / 1.643°C = 3.934 kJ/ °C

Step 4: Calculate moles of a 0.260 g sample of caffeine:

Moles caffeine = Mass caffeine / Molar mass caffeine

0.260 grams/ 194.19 g/mol = 0.0013389 moles

Step 5: Calculate heat released: for combustion of caffeine

Q = c * ΔT

Q = 3.934 kJ/°C * 1.436 °C = 5.65 kJ

Step 6: Calculate the heat of combustion per mole of caffeine

5.65 kJ / 0.0013389 moles = 4219.9 kJ/mol ≈ 4220 kJ/mol

The heat of combustion per moles of caffeine is 4220 kJ/mol

4 0

4 years ago

Which of the following is a type of matter

Ira Lisetskai [31]

Everything on Earth can be easily described in terms of one of four forms of matter: solid, liquid, gas, and plasma. Students are familiar with the three common forms of matter: solids, liquids, and gases. A solid is an object that has a form.

plz mark me as brainliest if this helped :)

7 0

4 years ago

Read 2 more answers

How is coal formed and why is it considered a nonrenewable resource? (Site 1)

Elanso [62]

Answer:

Coal is formed under the ground when pressure is high and there is a lot of heat also to make coal you need dead and composed organisms put together all of this makes a lump of dark coal.

Explanation:

6 0

3 years ago

Read 2 more answers

Problem PageQuestion Sulfuric acid is essential to dozens of important industries from steelmaking to plastics and pharmaceutica

Feliz [49]

The question is incomplete, here is the complete question:

Sulfuric acid is essential to dozens of important industries from steel making to plastics and pharmaceuticals. More sulfuric acid is made than any other industrial chemical, and world production exceeds 2.0×10¹¹ kg per year.

The first step in the synthesis of sulfuric acid is usually burning solid sulfur to make sulfur dioxide gas. Suppose an engineer studying this reaction introduces 1.8 kg of solid sulfur and 10.0 atm of oxygen gas at 650°C into an evacuated 50.0 L tank. The engineer believes Kp = 0.099 for the reaction at this temperature.

Calculate the mass of solid sulfur he expects to be consumed when the reaction reaches equilibrium. Round your answer to 2 significant digits.

Answer: The mass of solid sulfur that will be consumed is 19. grams

Explanation:

The chemical equation for the formation of sulfur dioxide gas follows:

$S(s)+O_2\rightarrow SO_2(g)$

Initial: 10.0

At eqllm: 10-x x

The expression of $K_p$ for above equation follows:

$K_p=\frac{p_{SO_2}}{p_{O_2}}$

We are given:

$K_p=0.099$

Putting values in above expression, we get:

$0.099=\frac{x}{10-x}\\\\x=0.901atm$

Partial pressure of sulfur dioxide = x = 0.901 atm

To calculate the number of moles, we use the equation given by ideal gas which follows:

$PV=nRT$

where,

P = pressure of the sulfur dioxide gas = 0.901 atm

V = Volume of the gas = 50.0 L

T = Temperature of the gas = $650^oC=[650+273]K=923K$

R = Gas constant = $0.0821\text{ L. atm }mol^{-1}K^{-1}$

n = number of moles of sulfur dioxide gas = ?

Putting values in above equation, we get:

$0.901atm\times 50.0L=n\times 0.0821\text{ L. atm}mol^{-1}K^{-1}\times 923K\\\\n=\frac{0.901\times 50.0}{0.0821\times 923}=0.594mol$

By stoichiometry of the reaction:

1 mole of sulfur dioxide gas is produced from 1 mole of sulfur

So, 0.594 moles of sulfur dioxide gas will be produced from = $\frac{1}{1}\times 0.594=0.594mol$ of sulfur

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Moles of sulfur = 0.594 moles

Molar mass of sulfur = 32 g/mol

Putting values in above equation, we get:

$0.594mol=\frac{\text{Mass of sulfur}}{32g/mol}\\\\\text{Mass of sulfur}=(0.594mol\times 32g/mol)=19.008g$

Hence, the mass of solid sulfur that will be consumed is 19. grams

8 0

4 years ago

Through which of the following ways can heat be transferred?

SashulF [63]

Answer:

The correct option is:

A) by direct or indirect contact between objects at different temperatures

Explanation:

Heat can be transferred in three different methods:

Conduction, Convection and Radiation

Conduction is heat transfer through direct contact between substances at different temperatures.

Convection is the heat transfer which takes place through air currents.

Radiation is the heat transfer that does not require contact between two objects.

Hence, heat transfer can take place through direct or indirect contact between objects at different temperatures.

4 0

3 years ago