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3 years ago

HELP THIS IS SCIENCE: what is difference between the pupil and the iris?

Chemistry

1 answer:

Scrat [10]3 years ago

3 0

Answer:

Pupil is the blackness in the middle, which is technically a "hole" in your eye which light goes through. The iris is the part that has color.

Explanation:

When someone asks you "what color are your eyes," they really mean "what color are your irises"

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Which statement is correct about the rate of chemical reactions?

ratelena [41]

Answer:

It increases when a catalyst is added.

Explanation:

The following factors control reaction rates:

1. Nature of reactants

2. Concentration of the reactants or pressure of gaseous

3. Temperature

4. Presence of catalyst

5. Sunlight

The addition of a foreign body to a reaction may influence the speed of the reaction. If a foreign body increases the rate of reaction, it is a called a positive catalyst or simply a catalyst. A negative catalyst is called an inhibitor.

A catalyst is a substance that is introduced into a chemical reaction to change the rate of the reaction without itself being affected at the end of the reaction.

Catalysts helps to reduce reaction time of many slow reactions. Most catalysts are specific in their actions and works on certain reactions or substrates.

Temperature change has a considerable effect on reaction rates since temperature is directly proportional to the average kinetic energy of reacting particles. Generally, reaction rate varies as temperature directly.

8 0

3 years ago

In a mixture of hydrogen and nitrogen gases, the mole fraction of nitrogen is 0.333. If the partial pressure of hydrogen in the

notka56 [123]

Answer:

$P_T=112.4torr$

Explanation:

Hello there!

In this case, since these problems about gas mixtures are based off Dalton's law in terms of mole fraction, partial pressure and total pressure, we can write the following for hydrogen, we are given its partial pressure:

$P_{H_2}=x_{H_2}*P_T$

And can be solved for the total pressure as follows:

$P_T=\frac{P_{H_2}}{x_{H_2}}$

However, we first calculate the mole fraction of hydrogen by subtracting that of nitrogen to 1 due to:

$x_{H_2}+x_{N_2}=1\\\\x_{H_2}=1-0.333=0.667$

Then, we can plug in to obtain the total pressure:

$P_T=\frac{75.0torr}{0.667}\\\\P_T=112.4torr$

Regards!

4 0

3 years ago

What is the isotope notation of the element that has an atomic number of 24 and a mass number of 52?

Fofino [41]

Answer:

Chromium

Explanation:

Cr has 24 atomic number and mass number 52

4 0

3 years ago

Use the standard reaction enthalpies given below to determine ΔH°rxn for the following reaction:P4(g) + 10 Cl2(g) → 4PCl5(s) ΔH°

miskamm [114]

<u>Answer:</u> The $\Delta H^o_{rxn}$ for the reaction is -1835 kJ.

<u>Explanation:</u>

Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.

According to this law, the chemical equation is treated as ordinary algebraic expressions and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the intermediate reactions.

The given chemical reaction follows:

$P_4(g)+10Cl_2(g)\rightarrow 4PCl_5(s)$ $\Delta H^o_{rxn}=?$