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2 years ago

15

Instead of collecting gas with a syringe, another method involves: • Submerging the evidence in a special agent • Placing a stri

p of charcoal in the airtight container • Using a tiny vacuum • All of the above

1 answer:

kirza4 [7]2 years ago

3 0

Using a tiny vacuum

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A chemist titrates 150.0 mL of a 0.2653 M carbonic acid (H2CO3) solution with 0.2196 M NaOH solution at 25 °C. Calculate the pH

xxTIMURxx [149]

Answer:

9.3

Explanation:

This is long and complicated so get ready

We are going to use the conjugate base of carbonic acid with water to make carbonic acid and OH- (Na is simply a spectator ion and is irrelavent here)

Let the conjugate base be A- and Carbonic acid be HA

A- + H20 ⇄ HA + OH-

To find the concentration of A- we must find the concentration of the reactants given. We know this will be equal because it is a strong base and all of it disassociates.

to get moles of acid we take the concentration and multiply by liters to cancel

.2653 x .150 = .039795 mol HA

Because it is at equivalence point we know the moles will be equal. We are given the concentration so we only have to solve for liters

We plug it into the equation and found: .181 L

Now use moles and combined volums to fins concentrarion which is .120 M

Now plug that use the Ka converted to Kb to find the cincentrations of HA and OH-

Ka is (10^-3.60) = 2.4E-4

Kb x Ka is 10^-14

Kb = 3.98E-11

Now we know Kb = [HA] [OH] / [A-]

Solve for this through algebra by using x for the values you dont know

youll find x^2 = 3.3E-10

X = 1.8 E -5

this is the OH- concentration

-log [oh] = pOH

pOH = 4.73

We know 14-pOH = ph so pH= 9.3

6 0

3 years ago

What is the formula for tin(IV) sulfide?<br> A. Sn4S<br> B. SnS2<br> C. Sns<br> D. SnS4

defon

Answer:

$SnS_{2}$

Explanation:

The formula for tin(IV) sulfide is SnS $_{2}$

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2 years ago

Genes are located in which part of a cell?

ddd [48]

Answer:A

Explanation:

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3 years ago

The p-value of a statistical test depends on all of the following, except:

vaieri [72.5K]

Answer:

The correct option is e.

Explanation:

p-value is the probability value for a given statistical model, the probability that, when the null hypothesis is true.

For two two samples the formula of test statistics is

$t=\frac{(\overline{x}_1-\overline{x}_2)-(\mu_1-\mu_2)}{\sqrt{\frac{s_1^2}{n_1}+\frac{s_2^2}{n_2}}}$

where,

$\overline{x}$ is sample mean

$\mu$ is population mean.

$s$ is standard deviation.

n is sample size.

Variance is the square of standard deviation.

It means variance, mean, numbers of samples is used in calculation of p-value.

Degree of freedom define the shape of the t-distribution that your t-test uses to calculate the p-value.

$d.f.=n_1+n_2-2$

p-value of a statistical test depends on all of the following, except median.

Therefore the correct option is e.

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3 years ago

In the formula 4H20, how many total hydrogen (H) atoms are there?

SashulF [63]

There are 8 total hydrogen (H) atoms.

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3 years ago

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