All categories

3 years ago

How many joules are needed to heat 20.0 g of Au from 10°C to 50°C? show work

Chemistry

1 answer:

AlexFokin [52]3 years ago

3 0

Answer:

297 J

Explanation:

The key to this problem lies with aluminium's specific heat, which as you know tells you how much heat is needed in order to increase the temperature of 1 g of a given substance by 1∘C.

In your case, aluminium is said to have a specific heat of 0.90Jg∘C.

So, what does that tell you?

In order to increase the temperature of 1 g of aluminium by 1∘C, you need to provide it with 0.90 J of heat.

But remember, this is how much you need to provide for every gram of aluminium in order to increase its temperature by 1∘C. So if you wanted to increase the temperature of 10.0 g of aluminium by 1∘C, you'd have to provide it with

1 gram0.90 J+1 gram0.90 J+ ... +1 gram0.90 J10 times=10×0.90 J

However, you don't want to increase the temperature of the sample by 1∘C, you want to increase it by

ΔT=55∘C−22∘C=33∘C

This means that you're going to have to use that much heat for every degree Celsius you want the temperature to change. You can thus say that

1∘C10×0.90 J+1∘C10×0.90 J+ ... +

You might be interested in

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

How much heat energy in megajoules is neede to convert 7kilograms of ice at negative 9 degrees to water at 0 degrees celsius

den301095 [7]

Heat_1: Get the ice to 0 degrees

Convert 7 kg to grams

7 kg [1000 grams / 1 kg] = 7000 grams

Heat needed to get the the ice from - 9 to 0

deltat = 0 - -9 = 9 degrees

m = 7000 grams

c = 2.1 joules/gram

Heat_1 = m*c*deltat

Heat_1 = 7000 * 2.1 * 9

Heat_1 = 132,300 joules

Heat_2: Melt the ice.

There is no temperature change. The formula is 333 j/gram

Formula: H = mass * constant

H = 7000 g * 333 J / gram

H = 2331000 joules

Heat_3: Total amount of Joules needed.

2331000 + 132300 = 2 463 300 joules

Convert to Megajoules

2 463 300 joules * 1 megajoule / 1000000 = 2.63 megajoules.

8 0

3 years ago

Barium (Ba) is in Group 2. Recall that atoms in Group 1 lose one electron to form ions with a 1+ charge. What type of ion does b

Marizza181 [45]

Barium is in group 2A, it looses 2 electrons to form the calcium ion BA2, i’ll send a picture of some of my notes, hopefully it helps:))

6 0

3 years ago

Question 6 The mineral barite, (BaSO.) has a ke of 1.1 x 10" at 25°C. Calculate the solubility of barium sulfate in water, in: 6

Sav [38]

Explanation:

(6.1). The reaction equation will be as follows.

$BaSO_{4}(s) \rightleftharpoons Ba^{2+}(aq) + SO^{2-}_{4}(aq)$

Assuming the value of $K_{sp}$ as $1.1 \times 10^{-10}$ and let the solubility of each specie involved in this reaction is "s". The expression for $K_{sp}$ will be as follows.