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3 years ago

What characteristics separate the class Insecta from other classes of the phylum Arachnida

Chemistry

1 answer:

inna [77]3 years ago

5 0

Answer:

Three pairs of walking legs, wings, body divided into three segments, pair of sensory antennae.

Explanation:

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Which is a physical change? A) Rusting iron B) Burning paper C) Reacting baking soda and vinegar D) Separating a mixture of salt

Deffense [45]

Answer:

Explanation:

7 0

3 years ago

How is a scientific law different from other laws in society?

Lemur [1.5K]

Answer:

The answer will be A

Explanation:

A scientific law is based on repeated experiments or observations, that describe or predict a range of natural phenomena. A scientific law is something that is unexpected

7 0

4 years ago

Read 2 more answers

A 0.2436-g sample of an unknown substance was dissolved in 20.0 ml of cyclohexane. The density of cyclohexane is 0.779 g/ml. The

Viktor [21]

The depression in freezing point is related to molality of solution as follows:

$\Delta T_{f}=k_{f}m$

Here, $k_{f}$ is freezing point depression constant, for cyclohexane it is equal to 20°C kg/mol.

The value of freezing-point depression is 2.5 °C, molality can be calculated as follows:

$m=\frac{\Delta T_{f}}{k_{f}}=\frac{2.5 ^{o}C}{20 ^{o}C kg/mol}=0.125 mol/kg$

Molality is defined as number of moles of solute in 1 kg of solvent.

Here, solvent is cyclohexane, its volume is given 20.0 mL and density is 0.779 g/mol thus, mass of cyclohexane can be calculated as follows:

$m=d\times V=0.779 g/mL\times 20 mL=15.58 g$

Converting this into kg,

$1 g=10^{-3} kg$

Thus, 15.58 g will be 0.01558 kg.

Now, number of moles of unknown solute is related to its mass and molar mass as follows:

$n=\frac{m}{M}$

Putting the values of mass of solute which is 0.2436 or 0.0002436 kg

$n=\frac{ 0.0002436 kg}{M}$

Now, expression for molality of solution is:

$m=\frac{n_{solute}}{m_{solvent}}$

Putting all the values,

$0.125 mol/kg=\frac{0.0002436 kg}{M\times 0.01558 kg}$

Or,

$0.125 mol/kg=\frac{0.015635}{M}$

On rearranging,

$M=\frac{0.015635}{0.125 mol/kg}=0.1250 kg/mol$

Or,

$M=0.125 kg/mol(\frac{1000 g}{1 kg})=125 g/mol$

Therefore, molar mass of unknown sample is 125 g/mol

5 0

4 years ago

What mass of YCL3 forms when 10.0 grams of each reactant are combined?

Triss [41]

The mass of $YCl_3$ that would be formed will be 18.22 grams

<h3>Stoichiometric calculations</h3>

Let us first look at the balanced equation of the reaction:

$2Y + 3Cl_2 --- > 2YCl_3$

The mole ratio of Y to $Cl_2$ is 2:3.

Mole of 10.0 grams of Y = 10/88.9 = 0.11 moles

Mole of 10.0 grams $Cl_2$ = 10/71 = 0.14 moles

3/2 of 0.11 = 0.165. Thus, $Cl_2$ is limiting in availability.

Mole ratio of $Cl_2$ and $YCl_3$ = 3:2

Equivalent mole of $YCl_3$ = 2/3 x 0.14 = 0.093 moles.

Mass of 0.093 moles $YCl_3$ =0.093 x 195.26 = 18.22 grams

More on stoichiometric calculations can be found here: brainly.com/question/27287858

#SPJ1

5 0

2 years ago

How does dalton's atomic theory support the law of conservation of mass?

n200080 [17]

Hi Amandadog,

Dalton stated that atoms are indestructible, indivisible particles that cannot change identity in a chemical reaction.

Hope this helps!
-Timmeh

7 0

3 years ago