All categories

2 years ago

A chemical reaction takes place to allow hand warmers to give off heat. This is an example of a(n) __________.

Chemistry

2 answers:

Dvinal [7]2 years ago

8 0

Answer:

Explanation:

Gives off heat,.

Sphinxa [80]2 years ago

3 0

Answer:

Exothermic

Explanation:

Exothermic reactions release heat, endothermic absorb heat, and precipitate is a solid formed from a solution

You might be interested in

how does the main function of the nervous system help the body react to internal and external stimuli??

Irina-Kira [14]

Nerves send signals to your brain from your spinal cord. If something is burning your nerves will send a pain signal from the area of the burn to your brain through you spinal cord. Then your brain sends a signal back to the nerves that there is pain and you should avoid it. Same with internal nerves and same with touch.

6 0

2 years ago

How does molarity and molality affect the concentration of a solution explain.

kolbaska11 [484]

Concentration of a solution can be expressed in terms of molarity and molality

Molarity is the number of moles of solute in a liter of a solution.

Molarity (M) = Moles of solute/Volume(litres) of solution

Molality is the number of moles of solute in one kg of the solution

Molality (m) = Moles of solute/Mass (kg) of solution

Therefore if the volume or the mass of the solution is changed this would affect the concentration.

In addition, volume is a quantity which depends on temperature. However, mass is independent of temperature. Therefore any changes in temperature, can also bring about a change in the molarity of the solution.

5 0

3 years ago

Write the rates for the following reactions in terms of the disappearance of reactants and appearance of products: (a) 302 .....

Oduvanchick [21]

Answer:

Explanation:

$\mathbf{From \ the \ information \ given:} \\ \\ \mathbf{The \ rates \ of \ the \ f ollowing \ reactions \ can \ be \ expressed \ as \ follows:}$

(a)

$\mathbf{3O_2 \to 2O_3} \\ \\ \\ \mathbf{-\dfrac{1}{3}\dfrac{d[O_2]}{dt}=\dfrac{2}{3} \dfrac{d[O_3]}{dt}}$

(b)

$\mathbf{C_2H_6 \to C_2H_4 + H_2} \\ \\ \\ \mathbf{ -\dfrac{d[C_2H_6]}{dt}= \dfrac{d[C_2H_4]}{dt}=\dfrac{d[H_2]}{dt}}$

(c)

$\mathbf{ClO^-+Br^- \to BrO^-+Cl^-} \\ \\ \\ \mathbf{ -\dfrac{d[ClO^-]}{dt}= -\dfrac{d[Br^-]}{dt} = \dfrac{d[BrO^-]}{dt} = \dfrac{d[Cl^-]}{dt} }$

(d)

$\mathbf{(CH_3)_3 CCl+H_2O \to (CH_3)_3COH + H^+ + Cl^-} \\ \\ \\ \mathbf{- \dfrac{d[(CH_3)_3CCl}{dt}= - \dfrac{d[H_2O]}{dt}= \dfrac{d[CH_3)_3COH}{dt}= \dfrac{d[H^+]}{dt}= \dfrac{d[Cl^-]}{dt}}$

(e)

$\mathbf{2AsH_3 \to 2As + 3H_2} \\ \\ \\ \mathbf{-\dfrac{1}{2}\dfrac{d[AsH_3]}{dt}=\dfrac{1}{2}\dfrac{d[As]}{dt}=\dfrac{1}{3}\dfrac{d[H_2]}{dt}}$

5 0

2 years ago

PLEASE HELP!?!.!,! What are the products of the combustion of a hydrocarbon?

Tatiana [17]

Answer:

carbon dioxide and water

Explanation:

Example: Combustion of Methane (CH₄(g))

CH₄(g) + 2O₂(g) => CO₂(g) + 2H₂O(g)**

____________________

Note: The combustion of any hydrocarbon produces CO₂ & H₂O. That is,

Ethane (C₂H₆) + O₂ => CO₂(g) + H₂O(g)

Propane (C₃H₈) + O₂ => CO₂(g) + H₂O(g)

Butane (C₄H₁₀) + O₂ => CO₂(g) + H₂O(g)

The issue remaining is to balance the reaction equation. For these type equation balance Carbon 1st, then Hydrogen and finish with Oxygen. Balancing in this order leaves Oxygen which can be balanced using fractions. If problem requires lowest whole number ratios of elements, simply multiply entire equation by 2 to get standard equation*

______________________

*Standard Equation is defined as the smallest whole number ratios of elements. The 'standard equation' is significant in that it is assumed to be at STP conditions; i.e., 0⁰C (=273K) & 1.0 Atmosphere pressure.

Ethane (C₂H₆) + 7/2O₂(g) => 2CO₂(g) + 3H₂O(g)

=> 2C₂H₆ + 7O₂(g) => 4CO₂(g) + 6H₂O(g) <= Standard Form of Rxn

Propane (C₃H₈) + 5O₂(g) => 3CO₂(g) + 4H₂O(g) <= Standard Form of Rxn (no need to balance with the '2' multiple)

Butane (C₄H₁₀) + 13/2O₂ => 4CO₂(g) + 5H₂O(g)

=> 2C₃H₈ + 13O₂(g) => 4CO₂(g) + 5H₂O(g) <= Standard Form of Rxn

______________________

**Also, note that water, H₂O(g), is listed as a gas. In some cases it will be listed as a liquid, H₂O(l).

3 0

3 years ago

Read 2 more answers

An electron has an uncertainty in its position of 513 pm. What is the uncertainty in its velocity?

ella [17]

"The uncertainty in velocity is Δv=1.05⋅105m/s . According to the Heisenberg Uncertainty Principle, you cannot measure simultaneously with great precision both the momentum and the position of a particle. m - the mass of an electron - 9.10938⋅10−31kg."
-socratic.com

7 0

3 years ago