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3 years ago

How much calcium hydroxide in grams is needed to produce 1.5 l of a 0.25m solution?

1 answer:

6 0

The mass ca(Oh)2 needed to produce 1.5 l of 0.25 solution is calculated as follows
find moles

=moles = molarity x volume

moles is therefore = 1.5 x 0.25 = 0.375 moles

mass = moles x molar mass
0.375mol x 74.09 g/mol = 27.78 grams

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For the following reaction, 4.34 grams of sulfur dioxide are mixed with excess oxygen gas . The reaction yields 3.89 grams of su

Degger [83]

Answer:

5.42g, 71.77%

Explanation:

First, we have to write out the balanced chemical equation. The unbalanced equation can be written as “SO2+O2 -> SO3” and to balance it, we can see that having two mols of SO2 and two mols of SO3 will make each side have the same amount of mols per element on each side. So the balanced chemical equation is “2SO2 + O2 -> 2SO3”

Now, we want to solve for the theoretical yield in grams of SO3. To do this, we have to use dimensional analysis. We convert g SO2 into mols SO2 using the molar mass of the elements. Then we convert mols of SO2 into mols of SO3 using the balanced equation. Once we’ve done that, we can convert mols of SO3 into grams of SO3.

You should know how to look up the molar mass of elements on the periodic table by now. Find the masses and set up the terms so they cancel like so:

$4.34g \times \frac{1mol \: so2}{64.07g \: so2} \times \frac{2 \: mol \: so3}{2 \: mol \: so2} \times \frac{80.07gso3}{1 \: mol \: so3}$

Doing the math, we get 5.42g so3 as the theoretical yield. This is the most amount that you could ever get if the world was a perfect place. But alas, it isn’t and mistakes are gonna happen, so the number is going to be less than that. So the best we can do, is to figure out the percent yield that we got.

In a lab scenario, this was calculated to be 3.89 g as stated by the problem. The percent composition formula is

$| \frac{result}{expected \: result} | \times 100$

and plugging the numbers into it, we get:

$| \frac{3.89}{5.42} | \times 100 = 71.77\%$

make sure to follow the decimal/significant figure rules of your instructor, but only round at the end. My professor didn't care too much thankfully, but some professors do

6 0

2 years ago

I'm not 100% sure of the answer. Explanations are highly appreciated.

PolarNik [594]

Answer:

The correct answer is

$\Delta H=2(1072)+498 -4(799)$

Explanation:

Enthalpy of reaction :

It is the amount of energy released/absorbed when one mole of the substance is formed from the reactant at a constant pressure.

The enthalpy of a reaction can be calculated using :

$\Delta H=\Delta H_{reactants}-\Delta H_{products}$

$2CO+O_{2}\rightarrow 2CO_{2}$

$\Delta H_{reactants}=2(C\equiv O)+O=O$

$\Delta H_{reactants}=2(1072)+498$

$H_{products}=2(2\times C=O)$

$H_{products}=4\times 799$

$\Delta H=\Delta H_{reactants}-\Delta H_{products}$

$\Delta H=2(1072)+498 -4(799)$

$units = \frac{kJ}{mole}$

Please note that :

The carbon monoxide , CO should be taken as C triple bond O. Not C=O .

So , the bond energy =1072 is used

$\Delta H=2(1072)+498 -4(799)$

8 0

3 years ago

24.3 2 An artifact classified as seeds, found in a site at Newlands Cross, Ireland, is found to have a 14C radioactivity of 0.10

Rina8888 [55]

Answer:

Age ≅ 7500 years

Explanation:

All radioactive decay is 1st order kinetics and described by the expression

A = A₀e^-kt => t = ln(A/A₀) / -k

k = 0.693 / t(half life) = (0.693 / 5730)yrs⁻¹ = 1.21 x 10⁻⁴ yrs⁻¹

t = Age = [ln(0.103/0.255) / - 1.21 x 10⁻⁴] yrs = 7500 years

5 0

3 years ago

Describe the flow of blood to the human body, including through each of the four chambers of the heart. Explain how the blood ch

xeze [42]

Hey there,

The blood needs to flow at a great and constant speed. It can not flow very slow because that can be warning's of a heart attack because your blood is using alot of force and its trying to provide as much blood as possible to arrive at the heart in order for your body to live. This is why we should drink water because as we drink water, it helps our blood flow through out our body well and so that we ma not have any problem now and in the future.

~Jurgen

3 0

3 years ago

Read 2 more answers

3. A student carries out the clay-catalyzed dehydration of cyclohexanol starting with 10 moles of cyclohexanol and obtains 500 m

IrinaK [193]

Answer:

$49.45~%$

Explanation:

In this case, we have to start with the chemical reaction:

$C_6H_1_2O~->~C_6H_1_0~+~H_2O$

So, if we start with 10 mol of cyclohexanol ( $C_6H_1_2O$ ) we will obtain 10 mol of cyclohexanol ( $C_6H_1_0$ ). So, we can calculate the grams of cyclohexanol if we calculate the molar mass: