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2 years ago

How many grams of nacl are required to make 250. 00 ml of a 3. 000 m solution?

1 answer:

3 0

Molarity (M) = moles of solute (mol) / Volume of the solution (L)

Molarity of the solution = 3.000 M
Volume of the solution = 250.0 mL
0.25 moles in 250.0 mL
= molarity x volume of the solution

= 3.000 M x 0.25 L
= 0.75 mol

Hence, 0.75 mol of NaCl is needed to prepare 250.0 mL of 3.000 M NaCl solution.

Moles of NaCl in 250.0 mL = 0.75 mol
Molar mass of NaCl = 58.44 g/mol
Mass of NaCl in 250.0 mL = Moles x Molar mass

Hence, 43.83 g of NaCl is needed to prepare 250.0 mL of 3.000 M solution.

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37 cos(x2) dx 0 Do the following. (a) Find the approximations T8 and M8 for the given integral. (Round your answer to six decima

dusya [7]

The approximations T8 and M8 for the given integral are:

T8 = 33.386321; and
M8 = 33.50794

<h3>What is an integral?</h3>

An Integral is a variable of which a given function is the derivative, i.e. it gives that function when differentiated and may express the area under the curve of the function's graph.

<h3>What is the explanation to above answer?</h3>

Given:

F(x) = 37 cox (x²)

Internal = [0,1] n = 8 in Δ x = 1/8

The sub intervals are:

[0, 1/8], [1/8, 2/8], [2/8, 3/8], [ 3/8, 4/8], [ 4/8, 5/8], [ 5/8, 6/8], [6/8, 7/8], [ 7/8, 1]

The mid points are given as:

1/16, 3/16, 5/16, 7/16, 9/16, 11/16, 13/16, 15/16

and X₀ = 0, X₁ = 1/8, X₂ = 2/8

Using the Trapezium Rule which states that:

$\int\limits^1_0 cos(x)^{2} } \, dx$ = Δx/2 $[f(xo) + 2f(x1) 2f(x2) + ....+ 2f(x7) + f(x8)]$

= 1/1Q[f(0) + 2f (1/8) + 2f(2/8) + ....+ 2f(7/8) + f(1)]

= 0.902333

Now

T8 = $\int\limits^1_0 {37Cos(x)^{2} } \, dx$

= $37\int\limits^1_0 {(0.902333)} } \, dx$

= 37 (0.902333)

T8 = 33.386321

It is to be noted that the midpoints rule is given as;

$\int\limits^1_0 {Cos(x)^{2} } \, dx$ = Δx [f(1/16) + (3/16) + .... + f(15/16)]

= 1/8[f(1/16) + f (3/16) + f(5/16) + f(7/16) + f(9/16) + f(11/16) + f(13/16) + f(15/16)]

= 0.905620

From the above,

M8 = $\int\limits^1_0 {37 Cos(x)^{2} } \, dx$

= $37\int\limits^1_0 {Cos(x)^{2} } \, dx$

= 37 (0.905620)

M8 = 33.50794

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6 0

2 years ago

A grocery store has two recycling machines

Thepotemich [5.8K]

Answer is 112%

kinda skeptical about my answer but i am going to give it my best shot, sorry if i get it wrong.

In percent-type questions I always go by this formula:

not a % %

original number : 100%

new number : new %

original number × new % = new number × 100%

here, the original numbers are 240 and 180 and the new % is +30% and -10% now let plastic be P and metal be M and let's elaborate this a bit further

plastic:

the first recycling machine took in 240 plastic bottles while the second took in 30% <u>more</u> plastic bottles, what we have to do here is to find out how much bottles the second machine took in as a form of integer, which is the new number; let that new number be X, let's plug this in the formula

$240:100+30\\X:130 \\$

notice: 130 is the new %

$240*130 = 100X\\31200 = 100X\\312=X$

the second machine took in 312 plastic bottles, let's save this answer for later

metal:

the first recycling machine took in 180 metal cans while the second took in 10% <u>less</u> plastic bottles, we do the same thing and find the new number, this time let it be Y:

$180:100-10\\Y=90$

90 is the new % here; also, notice how sometimes you either add or subtract percents, depending on what the problem demands.

$180*90=100Y\\16200=100Y\\162=Y$

Now we can conclude that the first recycling machine took in 240 plastic bottles and 180 metal cans and the second took in 312 plastic bottles and 162 metal cans.

here comes the hardest bit to apprehend and the final part of this problem, "the second machine recycled what percent (%) more items than the first?"

in other words, how much percent did the second machine recycle more.

to find that percent, first we need to add the plastic and metal "items" of both machines individually and turn them into percents: let the first machine be A and second machine be B:

A: 240+180=420

B: 312+162=474

again, using the same formula to find the new percent, let that percent be Z; plugging both A and B respectively:

$420:100\\474:Z$

$420Z=474*100\\420Z=47400\\Z= 112.857$ ≈ 112% more items than the first

now if you check the rounded up 112 and plug it back in to make sure of your answer: $420Z=47400$ you end up getting 47040, since it's rounded up, but when you plug the full 112.857 you get 47399.94, closest to 47400. Tip: when you plug in any value for check up, don't use the rounded up one.

At last, those steps are actually fast, especially with that formula it's so important. the explanation seems intimidating so read it slowly and take your time. if you have any other questions, feel free to ask. also, let me know if you know a faster method to solve this question. <3

4 0

3 years ago

which explanation best explains the importance of using encryption? it is important to learn a new language. it is fun and inter

Vladimir [108]

Encryption protects sensitive information is explanation best explains the importance of using encryption. Personal information and important information are protected, and communication between client apps and servers is made more secure.

<h3>What is Encryption?</h3>

Encryption is a way of securing digital data that employs one or more mathematical procedures, as well as a password or "key" to decrypt the information.

Data is encrypted using an algorithm that makes the original data unreadable. The name of two different data comes from the fact that encryption and decryption are done with the same key.

Thus option C is correct.

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8 0

2 years ago

Neurofeedback, a newer type of biofeedback, involves trying to change

frosja888 [35]

Neurofeedback involves trying to change brain wave activity.

<h3>Brain wave</h3>

The human brain is an intricate organ that baffles many scientists today. One design feature of the human brain is its ability to send signals in the form of brain waves when the mind is ar work or in a state of rest. These brain wave activity are braodly categorized into four types, namely;

beta waves
alpha waves
theta waves
delta waves

Neurofeedback thus occurs when an attempt is made to change from one of the above brain wave types to another.

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2 years ago

Which of the following x-values satisfy the inequality 7/6 + x/2< x - 1/3 ?

Anettt [7]

Answer: Any x-values greater than 3

Explanation:

$\frac{7}{6} +\frac{x}{2} < x-\frac{1}{3} \\\\\frac{7}{6} +\frac{1}{3}$

5 0

3 years ago