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3 years ago

Why do all chemical changes occur

Chemistry

1 answer:

GenaCL600 [577]3 years ago

6 0

Answer:

Chemical Reactions. ... Reactions occur when two or more molecules interact and the molecules change. Bonds between atoms are broken and created to form new molecules.

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Bob, Jill, Kim, and Steve measure an object's length, density, mass, and brightness, respectively. Which student must derive a u

ValentinkaMS [17]

Answer:

The answer is Bob

Explanation:

The science exist to kinds of measurements base units and derive units of measurement.

Base units are the ones that measure: length, mass, time, electric current, temperature, luminous intensity and amount of substance.

Derivative units of measurement are obtain when we combine the base units.

Know from your question

Bob measures length is a base unit

Jill measures density is a derivative unit, is the combination of mass and volumen

Kim measures mass is a base unit

Steve measures brightness is a base unit.

8 0

3 years ago

Which of the following systems has potential energy only?

bagirrra123 [75]

Answer D

Explanation:

6 0

3 years ago

What is the number of grams of N₂ (g) that contains 1.80 x 10^24 molecules?

svet-max [94.6K]

Answer:

83.69 gm

Explanation:

molar weight of N2 = 28

Find the number of moles then multiply by this

1.8 x10^24/ (6.022x10^23) * 28 =83.69 gm

7 0

2 years ago

A monoprotic weak acid when dissolved in water is 0.66% dissociated and produces a solution with a pH of 3.04. Calculate the Ka

raketka [301]

Answer:

Ka = 6.02x10⁻⁶

Explanation:

The equilibrium that takes place is:

HA ⇄ H⁺ + A⁻

Ka = [H⁺][A⁻]/[HA]

We calculate [H⁺] from the pH:

pH = -log[H⁺]

[H⁺] = $10^{-pH}$

[H⁺] = 9.12x10⁻⁴ M

Keep in mind that [H⁺]=[A⁻].

As for [HA], we know the acid is 0.66% dissociated, in other words:

[HA] * 0.66/100 = [H⁺]

We calculate [HA]:

[HA] = 0.138 M

Finally we calculate the Ka:

Ka = $\frac{[9.12x10^{-4}]*[9.12x10^{-4}]}{[0.138]}$ = 6.02x10⁻⁶

3 0

3 years ago

People take antacids, such as milk of magnesia, to reduce the discomfort of acid stomach or heartburn. The recommended dose of m

Llana [10]

Answer:

$V_{HCl}=0.208L=208mL$

Explanation:

Hello,

In this case, since the chemical reaction is:

$2HCl+Mg(OH)_2\rightarrow MgCl_2+2H_2O$

We can see that hydrochloric acid and magnesium hydroxide are in a 2:1 mole ratio, which means that the neutralization point, we can write:

$n_{HCl}=2*n_{Mg(OH)_2}$

In such a way, the moles of magnesium hydroxide (molar mass 58.3 g/mol) in 500 mg are:

$n_{Mg(OH)_2}=500mg*\frac{1g}{1000mg}*\frac{1mol}{58.3g} =0.00858mol$

Next, since the pH of hydrochloric acid is 1.25, the concentration of H⁺ as well as the acid (strong acid) is:

$[H^+]=[HCl]=10^{-pH}=10^{-1.25}=0.0562M$

Then, since the concentration and the volume define the moles, we can write:

$[HCl]*V_{HCl}=2*n_{Mg(OH)_2}$

Therefore, the neutralized volume turns out:

$V_{HCl}=\frac{2*0.00858mol}{0.0562\frac{mol}{L} }\\ \\V_{HCl}=0.208L=208mL$

Best regards.

3 0

3 years ago