What type of compound is calcium oxide

yKpoI14uk [10]

The answer is b.low frequency,high energy

6 0

4 years ago

How many grams of sodium benzoate should be added to prepare the buffer? Neglect the small volume change that occurs when the so

expeople1 [14]

Answer:

$2.72$ grams

Explanation:

Complete question is

You are asked to pre pare a pH = 4.00 buffer starting from 1.50 L of 0.0200 M solution of benzoic acid

(C6H5COOH)

and any amount you need of sodium benzoate

(C6H5COONa)

How many grams of sodium benzoate should be added to prepare the buffer? Neglect the small volume change that occurs when the sodium benzoate is added.

Solution

Given

pH of the buffer solution $= 4$

Concentration of C6H5COOH $= 0.02$ M

Volume of the buffer solution $= 1.50$ L

$K_a$ value for benzoic acid is $6.3 * 10^ {-5}$

Concentration of sodium benzoate

$pH = - log Ka + log \frac{C6H5COONa}{C6H5COOH}$

Substituting the given values we get

$log \frac{C6H5COONa}{C6H5COOH} = 4 + log (6.3 * 10^ {-5})\\log \frac{C6H5COONa}{C6H5COOH} = -0.20\\\frac{C6H5COONa}{C6H5COOH} = 10^{-0.2}\\{C6H5COONa} = 10^{-0.2} * 0.02\\{C6H5COONa} = 0.63 * 0.02\\{C6H5COONa} = 0.0126 M$

Number of moles in sodium benzoate

$= 0.0126 * 1.5 \\= 0.0189 Mol$

Mass of sodium benzoate

$0.0189 mol * 144.147 \frac{g}{mol} \\= 2.72 g$

3 0

3 years ago

Balance the following equation: * 1, 1, 1 1, 3, 1 2, 3, 2 1, 3, 2

alexira [117]

1,3,2

The coefficient multiplied by the subscript will give you how many atoms of the element there are.

So, if we plug in 1,3,2
There will be 2 Nitrogen and 6 Hydrogen in the reactants side of the equation. To balance this on the other side, we must put a 2 in order to get 2 Nitrogen and 6 Hydrogen again.

6 0

3 years ago

What are the series of steps that form oxygen atoms?

maw [93]

Answer:

2.5.2 Atomistic Configurations of Oxygen in Silicon Crystals

Oxygen atoms are incorporated in the silicon lattice on an interstitial position (denoted by Oi), where the oxygen atom sits in an almost bond-centered position between two adjacent Si atoms [101]. Several of the local vibration modes are infrared (IR) active. The predominant IR line at 1104/cm (at room temperature) was calibrated with respect to other analytical methods, such as gas fusion and several radioactive techniques, and is used as the standard method for the quantitative determination of the oxygen content in as-grown silicon crystals (as-grown silicon usually contains only a negligible amount of precipitated oxygen).

6 0

3 years ago

scandium47 has a half-life of 35s. suppose you have a 45g sample of scadium 47 how much of the sample remains unchanged after 14

Yuliya22 [10]

Via the half-life equation we have:

$A_{final}=A_{initial}(\frac{1}{2})^{\frac{t}{h} }$

Where A is the amount initially and final amount after some time has passed, t is the time elapsed, h is the half life time and so:

$A_{final}=45(\frac{1}{2})^\frac{140}{35} = 2.8125g$

Therefore there will be 2.8125 grams left after 140 seconds.

7 0

4 years ago