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2 years ago

T or F? Sometimes energy is lost during a chemical reaction.

Chemistry

2 answers:

netineya [11]2 years ago

8 0

Answer:

True.

Energy can be sometimes lost in chemical reactions.

Explanation:

amid [387]2 years ago

6 0

Answer: True.

Explanation:

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A chemistry student must write down in her lab notebook the concentration of a solution of potassium chloride. The concentration

DerKrebs [107]

Answer:

3.65 g / ml correct to 3 sig. fig.

Explanation:

The computation of the concentration required is shown below:

As we know that

[A] = mass of solute ÷ volume of solution

Before that first find the mass of solute

Given that

Initial weight = 5.55g

And,

Final weight = 92.7 g

So,

Mass of KCl is

= 92.7 - 5.55

= 87.15 g ~ 87.2 g

Now the KCi is fully dissolved, so the volume is 23.9 ml

So, concentration is

= 87.2 g ÷ 23.9 ml

= 3.65 g / ml correct to 3 sig. fig.

6 0

3 years ago

To break the oxygen-oxygen bonds in a single O2 molecule, 1 × 10–18 J of energy is required. Which of the following wavelengths

Sonbull [250]

E = hc/(lamda)

The lamda symbol is wavelength, which this site does not have. I can represent it with an "x" instead.

Plancks constant, h = 6.626×10^-32 J·s

Speed of light, c = 3.00×10^8 m/s

The energy must be greater than or equal to 1×10^-18 J

1×10^-18 J ≤ (6.626×10^-32 J·s)*(3.0×10^8 m/s) / x

x ≤ (6.626×10^-32 J·s)*(3.0×10^8 m/s) / (1×10^-18 J)

x ≤ 1.99×10^-7 m or 199 nm

The wavelength of light must be greater than or equal to 199 nm

8 0

3 years ago

A cylinder contains 250 g of Helium at 200 K. The external pressure is constant at 1 atm. The temperature of the system is raise

Black_prince [1.1K]

Answer:

There is 96200 J or 96 kJ of heat released.

Explanation:

Step 1: Data given

Mass of helium = 250 grams

Temperature = 200 K

Temperature is raised by 74 K

The heat capacity of helium = 20.8 J/mol*K

Molecular weight for helium = 4 g/mol

Step 2: Calculate moles of Helium

Moles of Helium = mass of Helium / molar mass of helium

Moles of helium = 250 grams / 4g/mol

Moles of helium = 62.5 moles

Step 3: Calculate heat

Q = n*c*ΔT or

⇒ with Q = the heat released in Joule

⇒ with n = moles of helium = 62.5 moles

⇒ with c = the heat capacity of helium = 20.8 J/mol*K

⇒ with ΔT = the change in temperature = T2 - T1 = 74 K

Q = 62.5 mol * 20.8 J/mol*K * 74 K

Q = 96200 J = 96 kJ

Since the temperature is raised, this is an exothermic reaction. The heat is released.

There is 96200 J or 96 kJ of heat released.

8 0

3 years ago

In examining several amino acids, you want to identify the feature or features that differentiate one amino acid from another. W

sergiy2304 [10]

Your answer is C
amino acids are created by a bond of two carbon atoms and each carbon is part of a different group, one negative and one positive. when the chemical reactions occurs, it creates the several diff amino acids

4 0

3 years ago

Read 2 more answers

4. Explain what you’ve learned about significant figures. How many significant figures are in the measurement 0.03050 kg?

nasty-shy [4]

There are 4 significant figures! Start counting after the first non-zero digit :)

Hope this helps.

3 0

2 years ago