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3 years ago

7

Someone please help me with number 5. no idea what it is.

1 answer:

KATRIN_1 [288]3 years ago

5 0

Answer is Sodium Hydroxide.

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How many moles are equal to 89.23g of calcium oxide, CaO?

Katen [24]

1.59moles

Explanation:

Mass of CaO = 89.23g

Unknown

Number of moles = ?

Solution:

The mole is a unit of measurement in chemistry used to delineate the number of particles an atom contains.

A mole of a substance contains the avogadro's number of particles.

Number of moles = $\frac{mass}{molar mass}$

Molar mass of CaO = 40 + 16 = 56g/mol

Number of moles = $\frac{89.23}{56}$ = 1.59moles

learn more:

Number of moles brainly.com/question/1841136

#learnwithBrainly

8 0

3 years ago

3. Which of the following is not true for atoms? (4 points) They combine to form elements and molecules. They contain negatively

Taya2010 [7]

<h3><u>Answer;</u></h3>

They are made up of elements.

<h3><u>Explanation;</u></h3>

An atom is the smallest particle of matter that still retains the property of the element.
Two or more atoms combine to form elements or compounds. Elements are formed by two or more similar atoms, while compounds are formed by two or more different elements.
Atoms are made up of subatomic particles; protons, electrons and neutrons. Electrons are negatively charged, protons are positively charged while neutrons have no charge.

7 0

3 years ago

Which one of the following is not a valid expression for the rate of the reaction below? 4NH3 + 7O2 → 4NO2 + 6H2O Which one of t

Veseljchak [2.6K]

Answer : All of the above are valid expressions of the reaction rate.

Explanation :

The given rate of reaction is,

$4NH_3+7O_2\rightarrow 4NO_2+6H_2O$

The expression for rate of reaction for the reactant :

$\text{Rate of disappearance of }NH_3=-\frac{1}{4}\times \frac{d[NH_3]}{dt}$

$\text{Rate of disappearance of }O_2=-\frac{1}{7}\times \frac{d[O_2]}{dt}$

The expression for rate of reaction for the product :

$\text{Rate of formation of }NO_2=+\frac{1}{4}\times \frac{d[NO_2]}{dt}$

$\text{Rate of formation of }H_2O=+\frac{1}{6}\times \frac{d[H_2O]}{dt}$

From this we conclude that, all the options are correct.

3 0

3 years ago

What is the specific heat of a substance if 6527 J are required to raise the temperature of a 312 g sample by 15 degrees Celsius

Tanzania [10]

Answer:

1.395J/g°C

Explanation:

The following were obtained from the question:

Q = 6527J

M = 312g

ΔT = 15°C

C =?

Q = MCΔT

C = Q/MΔT

C = 6527/(312 x 15)

C = 1.395J/g°C

The specific heat capacity of the substance is 1.395J/g°C

3 0

3 years ago

Calculate the pH and fraction of dissociation ( α ) for each of the acetic acid ( CH 3 COOH , p K a = 4.756 ) solutions. A 0.002

marysya [2.9K]

Answer:

The degree of dissociation of acetic acid is 0.08448.

The pH of the solution is 3.72.

Explanation:

The $pK_a=4.756$

The value of the dissociation constant = $K_a$

$pK_a=-\log[K_a]$

$K_a=10^{-4.756}=1.754\times 10^{-5}$

Initial concentration of the acetic acid = [HAc] =c = 0.00225

Degree of dissociation = α

$HAc\rightleftharpoons H^++Ac^-$

Initially

c

At equilibrium ;

(c-cα) cα cα

The expression of dissociation constant is given as:

$K_a=\frac{[H^+][Ac^-]}{[HAc]}$

$1.754\times 10^{-5}=\frac{c\times \alpha \times c\times \alpha}{(c-c\alpha)}$

$1.754\times 10^{-5}=\frac{c\alpha ^2}{(1-\alpha)}$

$1.754\times 10^{-5}=\frac{0.00225 \alpha ^2}{(1-\alpha)}$

Solving for α:

α = 0.08448

The degree of dissociation of acetic acid is 0.08448.

$[H^+]=c\alpha = 0.00225M\times 0.08448=0.0001901 M$

The pH of the solution ;

$pH=-\log[H^+]$

$=-\log[0.0001901 M]=3.72$

3 0

3 years ago