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tensa zangetsu [6.8K]
3 years ago
13

Who was in control of Afghanistan when the U.S. and Allied forces invaded it in 2001?

Chemistry
2 answers:
IrinaVladis [17]3 years ago
7 0
<span>B. the Taliban. is the answer</span>
Aleksandr-060686 [28]3 years ago
3 0
The correct answer is B. the Taliban.
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Harvey kept a balloon with a volume of 348 milliliters at 25.0˚C inside a freezer for a night. When he took it out, its new volu
ad-work [718]

Initial volume of the balloon = V_{1}= 348 mL

Initial temperature of the balloon T_{1} = 25.0^{0}C + 273 = 298 K

Final volume of the balloon V_{2} = 322 mL

Final temperature of the balloon = T_{2} = ?

According to Charles law, volume of an ideal gas is directly proportional to the temperature at constant pressure.

\frac{V_{1} }{T_{1} } =\frac{V_{2} }{T_{2} }

On plugging in the values,

\frac{348mL}{298 K} =\frac{322 mL}{T_{2} }

T_{2} =276 K

Therefore, the temperature of the freezer is 276 K

5 0
3 years ago
Name: _________________ Temperature o fwater_25_degreecent.YOU MUST SHOW ALL CALCULATIONS TO RECEIVE CREDIT FOR THEM! DATA ANALY
Anton [14]

Answer:

1. 0.02 M

2. 0.01 M

3. 4×10⁻⁶

Explanation:

We know that V₁S₁ = V₂S₂

1.

Concentration of HCl = 0.05 M

end point comes at = 10 ml

So, concentration of OH⁻(aq) = [OH⁻(aq)] ⇒ (0.05 × 10) ÷ 25 ⇒ 0.02 M

2.

2mol of OH⁻(aq) ≡ 1 mole of Ca²⁺(aq)

[Ca²⁺] = 0.02 ÷ 2 = 0.01 M

3.

K_{sp} = [Ca²⁺(aq)] [OH⁻(aq)]²

Ca(OH)₂ (aq) ⇄ Ca²⁺ (aq) + 2OH⁻ (aq)

K_{sp} = [0.01 × (0.02)²] = 4×10⁻⁶

4.

If reaction is exothermic which means heat energy will get evolved as a result temperature of the reaction media will get increased during the course of the reaction. If temperature is externally increased, the reaction will go backward to accumulate extra heat energy.

5.

K_{sp} value describes the solubility of a particular ionic compound. The higher the K_{sp} value, the higher the Solubility will be.

6.

This may be due to uncommon ion effect. The process of other ions (K⁺ or Na⁺) may increase the solubility

4 0
3 years ago
What can be said about an exothermic reaction with a negative entropy change?.
pashok25 [27]
Spontaneous at low temperatures.
3 0
2 years ago
A single penny has a mass of 2.5 g. Abbie and James each measure the mass of a penny multiple times. Which statement about these
const2013 [10]
The question is missing the data sets.

This is the complete question:

A single penny has a mass of 2.5 g. Abbie and James each measure the mass of a penny multiple times. Which statement about these data sets is true? 

O Abbie's measurements are both more accurate and more precise than James'.

O Abbie's measurements are more accurate, but less precise, than James'. 

O Abbie's measurements are more precise, but less accurate, than James'. 

O Abbie’s measurements are both less accurate and less precise than James'. 

Penny masses (g)

Abbie’s data                                        

2.5, 2.4, 2.3, 2.4, 2.5, 2.6, 2.6 

James’ data


2.4, 3.0, 3.3, 2.2, 2.9, 3.8, 2.9

Answer: first option, Abbie's measurements are both more accurate and more precise than James'.

Explanation:


1) To answer this question, you first must understand the difference between precision and accuracy.

<span>Accuracy is how close the data are to the true or accepted value.
</span>

<span>Precision is how close are the data among them, this is the reproducibility of the values.</span>

Then, you can measure the accuracy by comparing the means (averages) with the actual mass of a penny 2.5 g.

And you measure the precision by comparing a measure of spread, as it can be the standard deviation.

2) These are the calculations:

Abbie’s data                      
                 
Average: ∑ of the values / number of values 

Average = [2.5 + 2.4 + 2.3 + 2.4 + 2.5 + 2.6 + 2.6 ] / 7 = 2.47 ≈ 2.5

Standard deviation: √  [ ∑ (x - mean)² / (n - 1) ] = 0.11


James’ data


Average = [2.4 + 3.0 + 3.3 + 2.2 + 2.9 + 3.8 + 2.9] / 7 = 2.56 ≈ 2.6


Standard deviation = 0.53

3) Conclusions:

1) The average of Abbie's data are closer to the accepted value 2.5g, so they are more accurate.

2) The standard deviation of Abbie's data is smaller than that of Jame's data, so the Abbie's data are more precise.
7 0
2 years ago
Read 2 more answers
Using the balanced equation below, how many moles of water can be produced when 4 grams of Hydrogen react? 2H2(g)+O2(g) —&gt; 2H
gavmur [86]

Answer:

4 × 10 g

Explanation:

Step 1: Write the balanced equation

2 H₂(g) + O₂(g) ⇒ 2 H₂O(I)

Step 2: Calculate the moles corresponding to 4 g of H₂

The molar mass of H₂ is 2.02 g/mol.

4 g × 1 mol/2.02 g = 2 mol

Step 3: Calculate the moles of H₂O produced from 2 moles of H₂

The molar ratio of H₂ to H₂O is 2:2. The moles of H₂O produced are 2/2 × 2 mol = 2 mol.

Step 4: Calculate the mass corresponding to 2 moles of H₂O

The molar mass of H₂O is 18.02 g/mol.

2 mol × 18.02 g/mol = 4 × 10 g

7 0
2 years ago
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