Chemistry, 19.07.2019 23:00 kay4451

Which symbol can be used to indicate a chemical reaction that takes place in the presence of a catalyst? a: 350° c b: pt c: 0.5 atm d: the triangle

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Answer from: Angela1998

The correct answer is option B i.e. Pt

Following are the reason for identifying it as a correct answer.

Option A reflects the temperature at which reaction has been performed. It doesn't signify use of catalyst.
Option B signifies that, Pt is employed as a foreign material in the reaction system. The role of this foreign material is to accelerate the reaction rate. Such material is referred as catalyst. With reference to catalyst, it must be noted that, Pt is a heterogeneous catalyst.
Option C signifies the pressure of reactant gas, at which reaction is carried out. atm is the unit of pressure of reactant gas.
Option D is the symbol that is very often used to depict that reaction is performed at higher temperature.

Thus, among all the available options, option B i.e. Pt is a correct answer

Answer from: pandamaknae2003

The symbol that can be used to indicate a chemical reaction that takes place in the presence of a catalyst is letter B: Pt. Platinum is the metal which is often used as a heterogeneous catalysts for several reactions. Catalyst lowers the activation barrier of reaction, thereby accelerating the reactions rates.

Answer from: Quest

where is the following

explanation:

Answer from: Quest

assuming that your periodic table has eighteen columns, you should highlight the four elements in the third column from the left of the table.

explanation

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the $3d$ have energy higher than those in the $4 s$ orbital while lower than those of the $4 p$ orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the $4s$ orbital is therefore filled right after $3p$ orbitals and before $3 d$ orbitals.

potassium has electron configuration $[\text{ar}] 4 s^{1}$ and calcium $[\text{ar}] 4 s^{2}$ . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration $[\text{ar}] 4 s^{2} \; 3d^{1}$ and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the $ns^{2} \; (n-1) p^{1}$ and should be highlighted as well.

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Which symbol can be used to indicate a chemical reaction that takes place in the presence of a catal...

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