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3 years ago

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In an acid-base titration, a student uses 21.35 mL of 0.150 M NaOH to neutralize 25.00 mL of H2SO4. How many moles of acid are i

n the flask?

1 answer:

GalinKa [24]3 years ago

3 0

Answer: There are 0.006 moles of acid in the flask.

Explanation:

Given: $V_{1}$ = 21.35 mL, $M_{1}$ = 0.150 M

$V_{2}$ = 25.0 mL, $M_{2}$ = ?

Formula used to calculate molarity of $H_{2}SO_{4}$ is as follows.

$M_{1}V_{1} = M_{2}V_{2}$

Substitute the values into above formula as follows.

$M_{1}V_{1} = M_{2}V_{2}\\0.15 M \times 21.35 mL = M_{2} \times 25.0 mL\\M_{2} = 0.1281 M$

As molarity is the number of moles of a substance present in a liter of solution.

Total volume of solution = $V_{1} + V_{2}$

= 21.35 mL + 25.0 mL

= 46.36 mL (1 mL = 0.001 L)

= 0.04636 L

Therefore, moles of acid required are calculated as follows.

$Molarity = \frac{no. of moles}{Volume (in L)}\\0.1281 M = \frac{no. of moles}{0.04635 L}\\no. of moles = 0.006 mol$

Thus, we can conclude that there are 0.006 moles of acid in the flask.

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Select ALL correct answers. The contact force is caused by: A. Atoms randomly crashing into each other B. The charged particles

Inessa [10]

Answer:

A. Atoms randomly crashing into each other

E. The force of one object pushing against the force of another object.

Explanation:

Forces can be classified into two categories based upon the the mode of transfer or application:

1. Contact forces

2. Non-contact forces

Contact forces are the ones which require the physical contact of the matter to get transferred and tend to create the affect. Whereas non-contact forces have the field property which transfers the affect of force from one point to another without any physical contact of the matter or the medium.

Atoms crashing onto each other have some mass and velocity which upon collision impacts the other atoms exerts a contact force.
The interaction between the charged particles due to their charges is always due to the electric field be it electron or proton, be it within an atom or out of an atom.
The force between any two objects pushing or pulling each other is also possible only due to contact.

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Classify each element. Note that another term for main group is representative, another term for semimetal is metalloid, and the

NikAS [45]

The question is incomplete, here is the complete question:

Classify each element. Note that another term for main group is representative, another term for semi-metal is metalloid, and the inner transition metals are also called the lanthanide and actinide series.

Hf, Am, In, Ta, As, Se, Rn

<u>Answer:</u>

Hafnium and tantalum are transition elements.

Americium is a inner transition element.

Indium, Selenium and Radon are main group elements.

Arsenic is a metalloid.

<u>Explanation:</u>

Main group elements are the elements which belong to s block and p block. They are also known as representative elements.

S-block elements are defined as the elements whose last electron enters s-sub shell. The general electronic configuration of these elements is $ns^{1-2}$

P-block elements are defined as the elements whose last electron enters p-sub shell. The general electronic configuration of these elements is $np^{1-6}$

Metalloids are defined as the elements which show intermediate properties between metals and non-metals. There are 7 metalloids in the periodic table. They are: Boron, Silicon, germanium, Arsenic, Antimony, Tellurium and Polonium.

Transition elements are known as d-block elements. D block elements are defined as the elements whose last electron enters d sub shell. The general electronic configuration of these elements is $[(n-1)d^{1-10}ns^{0-2}]$

Inner transition elements are known as (f block) elements. (F block) elements are defined as the elements whose last electron enters (f subshell). The general electronic configuration of these elements is $[(n-2)f^{1-14}(n-1)d^{0-1}ns^{2}]$ . They are also known as lanthanide and actinide series.

For the given elements:

<u>Option 1:</u> Hf

Hafnium is the 72nd element of the periodic table having electronic configuration of $[Xe]4f^{14}5d^26s^2$

As, the last electron is entering the d subshell, it is a transition element.

<u>Option 2:</u> Am

Americium is the 95th element of the periodic table having electronic configuration of $[Rn]5f^{7}6d^07s^2$

As, the last electron is entering the (f subshell), it is a inner transition element.

<u>Option 3:</u> In

Indium is the 49th element of the periodic table having electronic configuration of $[Kr]5s^25p^1$

As, the last electron is entering the p subshell, it is a main group element.

<u>Option 4:</u> Ta

Tantalum is the 73rd element of the periodic table having electronic configuration of $[Xe]4f^{14}5d^56s^2$

As, the last electron is entering the d subshell, it is a transition element.

<u>Option 5:</u> As

Arsenic is the 33rd element of the periodic table having electronic configuration of $[Ar]4s^24p^3$

As, the last electron is entering the p subshell, it is a main group element. It shows an intermediate property of metal and non-metal. Thus, it is a metalloid.

<u>Option 6:</u> Se

Selenium is the 34th element of the periodic table having electronic configuration of $[Ar]4s^24p^4$

As, the last electron is entering the p subshell, it is a main group element.

<u>Option 7:</u> Rn

Radon is the 86th element of the periodic table having electronic configuration of $[Xe]4f^{14}5d^{10}6s^26p^6$

As, the last electron is entering the p subshell, it is a main group element.

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