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3 years ago

I need help pls brainless if right

Chemistry

1 answer:

tatuchka [14]3 years ago

8 0

Answer: C

Jane Goodall observed the chimpanzees. She noted the chimpanzees, and she studied their bodies closely. This is an example of investigation.

Hope this helps you!

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After performing a dilution calculation, you determine you need 25.0 milliliters of an aqueous stock solution to make 100.0 mill

IRINA_888 [86]

A is obviously out because it leads to a volume of 125.0 milliliters of the new solution and gives you a lower concentration than you were aiming for.

D is out because you are adding 75 milliliters of the stock solution, so your concentration would be too high. You only need 25.0 milometers of stock solution per 100 milliliters of the new solution.

C is also out because it leads to 50.0 milliliters stock solution per 100 milliliters of the new solution and hence the wrong concentration.

B is by default the correct answer. It also details the correct technique. First you add the stock solution (This you know from your calculations to be 25 milliliters.) then you add the water up to the volume you needed. (Because the calculations only tell you the total volume of water not what you need to add) You also add the water last so you can rinse the neck of the flask to make sure you also get all the stock solution residue into the stock solution.

I would add the final step of stirring, but B is the only answer that can be correct.

8 0

4 years ago

Read 2 more answers

The following thermochemical equation is for the reaction of nitrogen(g) with oxygen(g) to form nitrogen dioxide(g). N2(g) + 2O2

Rzqust [24]

Answer: The mass of nitrogen gas reacted to produce given amount of energy is 5.99 grams.

Explanation:

The given chemical reaction follows:

$N_2(g)+2O_2(g)\rightarrow 2NO_2(g);\Delta H=66.4kJ$

We know that:

Molar mass of nitrogen gas = 28 g/mol

We are given:

Enthalpy change of the reaction = 14.2 kJ

To calculate the mass of nitrogen gas reacted, we use unitary method:

When enthalpy change of the reaction is 66.4 kJ, the mass of nitrogen gas reacted is 28 grams.

So, when enthalpy change of the reaction is 14.2 kJ, the mass of nitrogen gas reacted will be = $\frac{28}{66.4}\times 14.2=5.99g$

Hence, the mass of nitrogen gas reacted to produce given amount of energy is 5.99 grams.

8 0

4 years ago

What is the product of a force and the time during which the force acts

ELEN [110]

Impulse is the product of a force and the time during which that force acts on a body.

7 0

3 years ago

Stomach acid is approximately 0.10 M HCl. How many mL of stomach acid can be neutralized by one regular antacid tablet that cont

Radda [10]

Answer:

100 mL

Explanation:

The reaction that takes place is:

CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂

First we convert 500 mg of CaCO₃ into mmoles, using its molar mass:

500 mg ÷ 100 mg/mmol = 5 mmol CaCO₃

Then we convert 5 mmoles of CaCO₃ into HCl mmoles, using the stoichiometric coefficients of the balanced reaction:

5 mmol CaCO₃ * $\frac{2mmolHCl}{1mmolCaCO_3}$ = 10 mmol HCl

Finally we calculate the volume of a 0.10 M HCl solution (such as stomach acid) that would contain 10 mmoles:

10 mmol / 0.10 M = 100 mL

7 0

3 years ago

A student increases the temperature of a 200^3 cm balloon from 60°C to 120°C. What will the new volume of the balloon be? (Be ca

Darina [25.2K]

Explanation:

Given parameters:

Initial volume V1 = 200cm³

Initial temperature = 60°C

Final temperature = 120°C

Unknown:

Final volume = ?

Solution:

According to Charles law, at constant pressure, the volume of a given mass of gas is directly proportional to temperature.

mathematically;

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

1 and 2 are the initial and final states

V is the volume and T is the temperature

convert the temperature to kelvin

T1 = 60 + 273 = 333K

T2 = 120 + 273 = 393K

Input the parameters;

$\frac{200}{333} = \frac{V_{2} }{393}$

final volume is 236cm³

learn more:

Boyle's law brainly.com/question/8928288

#learnwithBrainly

7 0

3 years ago