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3 years ago

5

true or false: Mendeleev's arrangement of elements in the periodic table was based on the observations and experiments of his pr

ecessors who studied mass and properties of elements.

2 answers:

Oduvanchick [21]3 years ago

7 0

This answer is true

djyliett [7]3 years ago

6 0

I would agree. The answer is true

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A student carries out this chemical reaction in a beaker:

nydimaria [60]

Answer:The correct answer is option (C).

Explanation:

$Zn+CuCl_2\rightarrow Cu+ZnCl_2$

After the reaction between Zinc and copper(II) chloride, Zinc chloride and copper will be obtained as a product. This reaction occurs because zinc is more reactive than copper which displaces the copper from its aqueous solution.

The student will expect to find copper metal at bottom of the beaker with aqueous solution of zinc chloride.

Hence the correct answer is option (C).

7 0

3 years ago

Which solution contains the smallest number of moles of sucrose (c12h22o11, molar mass = 342.30 g/mol)? 2,000 ml of a 5.0 × 10–5

Iteru [2.4K]

> 2,000 mL of a 5.0 × 10–5% (w/v) sucrose solution

5.0 × 10–3 g/mL * 2000 mL * (1 mol / 342.30 g) = 0.0292 mol

<span>
> 2,000 mL of a 5.0 ppm sucrose solution</span>

5 grams / 1000000 mL * 2000 mL* (1 mol / 342.30 g) = 0.0000292 mol

<span>
> 20 mL of a 5.0 M sucrose solution </span>

5.0 M * 0.020 L = 0.1 mol

Answer:

<span>2,000 mL of a 5.0 ppm sucrose solution</span>

5 0

4 years ago

A sample of gas (1.9 mol) is in a flask at 21 °C and 697 mm Hg. The flask is opened and more gas is added to the flask. The new

Artyom0805 [142]

Answer: There are now 2.07 moles of gas in the flask.

Explanation:

$PV=nRT$

P= Pressure of the gas = 697 mmHg = 0.92 atm (760 mmHg= 1 atm)

V= Volume of gas = volume of container = ?

n = number of moles = 1.9

T = Temperature of the gas = 21°C=(21+273)K= 294 K (0°C = 273 K)

R= Value of gas constant = 0.0821 Latm\K mol

$V=\frac{nRT}{P}=\frac{1.9\times 0.0821 \times 294}{0.92}=49.8L$

When more gas is added to the flask. The new pressure is 775 mm Hg and the temperature is now 26 °C, but the volume remains same.Thus again using ideal gas equation to find number of moles.

$PV=nRT$

P= Pressure of the gas = 775 mmHg = 1.02 atm (760 mmHg= 1 atm)

V= Volume of gas = volume of container = 49.8 L

n = number of moles = ?

T = Temperature of the gas = 26°C=(26+273)K= 299 K (0°C = 273 K)

R= Value of gas constant = 0.0821 Latm\K mol

$n=\frac{PV}{RT}=\frac{1.02\times 49.8}{0.0821\times 299}=2.07moles$

Thus the now the container contains 2.07 moles.

6 0

3 years ago

What is the percent of O in<br> CO2?

katen-ka-za [31]

Answer:

72.7% of oxygen

Explanation:

8 0

3 years ago

A sealed 1.0L flask is filled with 0.500 mols of I_2 and 0.500 mols of Br_2. When the container achieves equilibrium the equilib

DochEvi [55]

Answer:

[IBr] = 0.049 M.

Explanation:

Hello there!

In this case, according to the balanced chemical reaction:

$I_2+Br_2\rightarrow 2IBr$

It is possible to set up the following equilibrium expression:

$K=\frac{[IBr]^2}{[I_2][Br_2]} =0.0110$

Whereas the the initial concentrations of both iodine and bromine are 0.50 M; and in terms of $x$ (reaction extent) would be:

$0.0110=\frac{(2x)^2}{(0.50-x)^2}$

Which can be solved for $x$ to obtain two possible results:

$x_1=-0.0277M\\\\x_2=0.0245M$

Whereas the correct result is 0.0245 M since negative results does not make any sense. Thus, the concentration of the product turns out:

$[IBr]=2x=2*0.0249M=0.049M$

Regards!

7 0

2 years ago