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3 years ago

How have safety concerns about chemicals changed over time?

Chemistry

1 answer:

Alex787 [66]3 years ago

8 0

Answer:

C. As scientists have learned more about chemicals, they have become more aware of their dangers

Explanation:

Chemicals are substances with standard compositions, held together by chemical bonds. Chemicals can exist in different phases such as solid, liquid, and gaseous phases. Over time, with a growing understanding of chemicals, their composition, and their reaction methods, scientists now have a better knowledge of the dangers chemicals can pose. To that effect, they have created standard safety measures for those who have to work with these chemicals.

When these guidelines are strictly adhered to, the chances of suffering accidents, burns, and explosions with these chemicals are significantly reduced.

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please hurry! If 3.87g of powdered aluminum oxide is placed in a container containing 5.67g of water, what is the limiting react

VikaD [51]

Answer:

Explanation:

Given parameters:

Mass of aluminium oxide = 3.87g

Mass of water = 5.67g

Unknown:

Limiting reactant = ?

Solution:

The limiting reactant is the reactant in short supply in a chemical reaction. We need to first write the chemical equation and convert the masses given to the number of moles.

Using the number of moles, we can ascertain the limiting reactants;

Al₂O₃ + 3H₂O → 2Al(OH)₃

Number of moles;

Number of moles = $\frac{mass}{molar mass}$

molar mass of Al₂O₃ = (2x27) + 3(16) = 102g/mole

number of moles = $\frac{3.87}{102}$ = 0.04mole

molar mass of H₂O = 2(1) + 16 = 18g/mole

number of moles = $\frac{5.67}{18}$ = 0.32mole

From the reaction equation;

1 mole of Al₂O₃ reacted with 3 moles of H₂O

0.04 mole of Al₂O₃ will react with 3 x 0.04 mole = 0.12 mole of H₂O

But we were given 0.32 mole of H₂O and this is in excess of amount required.

This shows that Al₂O₃ is the limiting reactant

6 0

2 years ago

The average propane cylinder for a residential grill holds approximately 18 kg of propane. How much energy (in kJ) is released b

brilliants [131]

Combustion is a chemical reaction between a fuel and an oxidant, oxygen, to give off combustion products and heat. Complete combustion results when all of the fuel is consumed to form carbon dioxide and water, as in the case of a hydrocarbon fuel. Incomplete combustion results when insufficient oxygen reacts with the fuel, forming soot and carbon monoxide.

The complete combustion of propane proceeds through the following reaction:
$C_{3} H_{8}$ + $5O_{2}$ --> $3CO_{2}$ + $4H_{2}O$

Combustion is an exothermic reaction, which means that it gives off heat as the reaction proceeds. For the complete combustion of propane, the heat of combustion is (-)2220 kJ/mole, where the minus sign indicates that the reaction is exothermic.

The molar mass of propane is 44.1 grams/mole. Using this value, the number of moles propane to be burned can be determined from the mass of propane given. Afterwards, this number of moles is multiplied by the heat of combustion to give the total heat produced from the reaction of the given mass of propane.

14.50 kg propane x 1000 g x 1 mole propane x 2220 kJ 
1 kg 44.1 g 1 mole

= 729,931.97 kJ

8 0

2 years ago

Sodium combines with water to produce sodium hydroxide and hydrogen gas. Which word equation represents this violent reaction?

zzz [600]

A coupleword to describe the action could be, Berserk, destructive, furious, unrestrained, impetuous, intemperate and uncontrollable

5 0

2 years ago

Which of the following generally determines if a reaction will occur?

Ratling [72]

Answer:

D - Thermodynamics

Explanation: I just took the quiz

4 0

1 year ago

a red box and a blue box are on the same shelf. There is more gravitational potential energy between the red box and Earth than

Anna [14]

Blue box. Gravitational potenti al energy changes into kinetic energy. The equation for gravitat ional potential energy is GPE = mgh, where m i s the mass in kilograms, g is the a cceleration due to gravity (9.8 on Earth), and h is the height above the ground in meters

8 0

2 years ago