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3 years ago

A cube has a mass of 42 grams and a volume of 15 cubic centimeters. What is it’s density?

Chemistry

1 answer:

deff fn [24]3 years ago

6 0

Answer:

2.8g/cm³

Explanation:

Given parameters:

Mass of cube = 42g

Volume of cube = 15cm³

Unknown:

Density of the cube = ?

Solution:

Density is defined as the mass per unit volume of a substance. It is mathematically expressed as:

Density = $\frac{mass}{volume}$

So;

Density = $\frac{42}{15}$ = 2.8g/cm³

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Why does an exothermic reaction need activation energy?

andrey2020 [161]

Answer:

Activation energy is needed so reactants can move together, overcome forces of repulsion, and to begin breaking bonds.

Explanation:

6 0

3 years ago

What volume (in liters) of a solution contains 0.14 mol of KCl?

oksano4ka [1.4K]

Answer:

$\boxed {\boxed {\sf 0.078 \ L }}$

Explanation:

We are asked to find the volume of a solution given the moles of solute and molarity.

Molarity is a measure of concentration in moles per liter. It is calculated using the following formula:

$molarity= \frac{moles \ of \ solute}{liters \ of \ solution}$

We know there are 0.14 moles of potassium chloride (KCl), which is the solute. The molarity of the solution is 1.8 molar or 1.8 moles of potassium chloride per liter.

moles of solute = 0.14 mol KCl
molarity= 1.8 mol KCl/ L
liters of solution=x

Substitute these values/variables into the formula.

$1.8 \ mol \ KCl/ L = \frac { 0.14 \ mol \ KCl}{x}$

We are solving for x, so we must isolate the variable. First, cross multiply. Multiply the first numerator and second denominator, then the first denominator and second numerator.

$\frac {1.8 \ mol \ KCl/L}{1} = \frac{0.14 \ mol \ KCl}{x}$

$1.8 \ mol \ KCl/ L *x = 1*0.14 \ mol \ KCl$

$1.8 \ mol \ KCl/ L *x = 0.14 \ mol \ KCl$

Now x is being multiplied by 1.8 moles of potassium chloride per liter. The inverse operation of multiplication is division, so we divide both sides by 1.8 mol KCl/L.

$\frac {1.8 \ mol \ KCl/ L *x}{1.8 \ mol \ KCl/L} = \frac{0.14 \ mol \ KCl}{1.8 \ mol \ KCl/L}$

$x= \frac{0.14 \ mol \ KCl}{1.8 \ mol \ KCl/L}$

The units of moles of potassium chloride cancel.

$x= \frac{0.14 }{1.8 L}$

$x=0.07777777778 \ L$

The original measurements of moles and molarity have 2 significant figures, so our answer must have the same. For the number we found, that is the thousandth place. The 7 in the ten-thousandth place tells us to round the 7 up to a 8.

$x \approx 0.078 \ L$

There are approximately 0.078 liters of solution.

5 0

3 years ago

Find the volume of 0.100M hydrochloric acid necessary to react completely with 1.51g Al(OH)3.

shtirl [24]

Reaction equation:
Al(OH)₃ + 3HCl → AlCl₃ + 3H₂O
Moles of Al(OH)₃:
moles = mass/Mr
= 1.51 / (27 + 17 x 3)
= 0.019
Molar ratio Al(OH)₃ : HCl = 1 : 3
Moles of HCl required = 0.019 x 3
=0.057
concentration = moles/volume
volume = 0.057 / 0.1
= 0.57 dm³
= 570 ml

3 0

3 years ago

Question 3 READ each trait and decide whether it is inherited or acquired,

rosijanka [135]

Answer:

1. inherited

2. inherited

3. inherited

4. acquired

5. acquired

6. acquired

7. acquired

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3 years ago

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Elena-2011 [213]

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3 years ago