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Salsk061 [2.6K]
3 years ago
10

PLEASE HELP BEFORE 7 A.M. PACIFIC TIME SEE ATTACHED.

Chemistry
2 answers:
pickupchik [31]3 years ago
7 0

Answer:

(i) 32.9 mL; (ii)  37.5 mL; (iii) 21.73 mL

Explanation:

You should always try to read a measuring instrument to a tenth of the smallest scale division.

Here, you are measuring liquids, so you take the scale reading from the bottom of the meniscus.

(i) Graduated cylinder

There are 10 divisions between 30 mL and 40 mL, so each division represents 1 mL.

The level of the liquid appears to be between 32 mL and 33 mL. It is much closer to 33 mL (perhaps right on 33 mL).

You should report the volume to the nearest 0.1 mL. I would read the volume as 32.9 mL, but 32.8 and 33.0 are also acceptable.

Note: If you think the level is right on the 33 mark, you report the volume as 33.0 mL (NOT 33 mL).

(ii) Thermometer

The reading is about half-way between 87 ° and 88 °.

I would report the temperature as 87.5 °, but 87.4 ° and 87.6 ° would also be acceptable.

(iii) Buret

There are 10 divisions between 21 mL and 22 mL, so each division represents 0.1 mL.

You should estimate to the nearest 0.01 mL.

The liquid level is about a third of the way from 21.7 mL to 21.8 mL.

I would report the volume as 21.73 mL, but 21.72 mL and 21.74 mL are also acceptable.

 

anastassius [24]3 years ago
5 0
For i: 33mL
For ii: 87-88mL
For iii:22.3mL
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dmitriy555 [2]

<u>Answer:</u> The mass of cryolite produced is 51.48 kg

<u>Explanation:</u>

To calculate the number of moles, we use the equation:

\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}      .....(1)

  • <u>For aluminium oxide:</u>

Given mass of aluminium oxide = 12.5 kg = 12500 g    (Conversion factor:  1 kg = 1000 g)

Molar mass of aluminium oxide = 101.96 g/mol

Putting values in equation 1, we get:

\text{Moles of aluminium oxide}=\frac{12500g}{101.96g/mol}=122.6mol

  • <u>For NaOH:</u>

Given mass of NaOH = 55.4 kg = 55400 g

Molar mass of NaOH = 40 g/mol

Putting values in equation 1, we get:

\text{Moles of NaOH}=\frac{55400g}{40g/mol}=1389mol

  • <u>For HF:</u>

Given mass of HF = 55.4 kg = 55400 g

Molar mass of HF = 20 g/mol

Putting values in equation 1, we get:

\text{Moles of HF}=\frac{55400g}{20g/mol}=2770mol

For the given chemical reaction:

Al_2O_3(s)+6NaOH(l)+12HF(g)\rightarrow 2Na_3AlF_6+9H_2O(g)

By Stoichiometry of the reaction:

1 mole of aluminium oxide reacts with 6 moles of sodium hydroxide and 12 moles of HF.

So, 122.6 moles of aluminium oxide will react with (6\times 122.6)=735.6mol of sodium hydroxide and (12\times 122.6)=1471.2mol of HF

As, given amount of NaOH and HF is more than the required amount. So, they are considered as an excess reagent.

Thus, aluminium oxide is considered as a limiting reagent because it limits the formation of product.

By Stoichiometry of the reaction:

1 mole of aluminium oxide produces 2 moles of cryolite

So, 122.6 moles of aluminium oxide will produce = \frac{2}{1}\times 122.6=245.2mol of cryolite

Now, calculating the mass of cryolite by using equation 1:

Molar mass of cryolite = 209.94 g/mol

Moles of cryolite = 245.2 mol

Putting values in equation 1, we get:

245.2mol=\frac{\text{Mass of cryolite}}{209.94g/mol}\\\\\text{Mass of cryolite}=(245.2mol\times 209.94g/mol)=51477.3g

Converting this into kilograms, we use the conversion factor:

1 kg = 1000 g

So, 51477.3 g\times (\frac{1kg}{1000g})=51.48kg

Hence, the mass of cryolite produced is 51.48 kg

7 0
3 years ago
If you push on a wall with 200n with what forth with the wall push back
sweet-ann [11.9K]
According to newtons law every action has a equal reaction therefore it will push back 200n aswell
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Which substance produces hydroxide ions in solution?
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An Arrhenius Base

Explanation:

The definition of this is a base that is a hydroxide ion donor.

8 0
3 years ago
What do you use to determine molar mass?
levacccp [35]

Answer:

the molar mass of any element can be determined by finding the atomic mass of the element on the periodic table for example, if the atomic mass of sulfer is 32.066 amu, then it's molar mass is 32.066 g / mol

5 0
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4. A student started with a 0.032 g sample of copper which he took through the series of reactions described in this experiment.
Elodia [21]

Answer:

Y=48.6\%

Explanation:

Hello,

In this case, we can consider the following chemical reaction for the oxidation of copper which only occurs at high temperatures:

2Cu+O_2\rightarrow 2CuO

In such a way, for 0.032 grams of copper, the following grams of copper (II) oxide (black product) are yielded:

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Therefore, the percent yield is:

Y=\frac{0.038g}{0.078g}*100\%\\ \\Y=48.6\%

Best regards.

6 0
3 years ago
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