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gogolik [260]
3 years ago
15

Which of these indicate that a chemical reaction has occurred?

Chemistry
2 answers:
Pepsi [2]3 years ago
6 0
Your answer is C - Melting of a substance 
tigry1 [53]3 years ago
3 0

I think b.)  cause its evaporating


;)

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(GIVING BRAINLYIST) How does temperature and precipitation change as you increase in elevation?
S_A_V [24]

Answer:

Temperature gets cooler and precipitation increases.

Explanation:

As average temperatures at the Earth's surface rise, more evaporation occurs, which, in turn, increases overall precipitation. … In addition, higher temperatures lead to more evaporation, so increased precipitation will not necessarily increase the amount of water available for drinking, irrigation, and industry

Higher elevations cause temperatures to drop because the higher up in the atmosphere you go, the colder it gets due to air pressure, in turn causing precipitation to freeze, creating snow. Lower elevations are a lot warmer because the air pressure is not as pressurized causing the temperature to be warmer

7 0
2 years ago
Read 2 more answers
A first-order reaction is 45% complete at the end of 43 minutes. What is the length of the half-life of this reaction
shtirl [24]

The half-life of the reaction is 50 minutes

Data;

  • Time = 43 minutes
  • Type of reaction = first order
  • Amount of Completion = 45%

<h3>Reaction Constant</h3>

Let the initial concentration of the reaction be X_0

The reactant left = (1 - 0.45) X_0 = 0.55 X_0 = X

For a first order reaction

\ln(\frac{x}{x_o}) = -kt\\ k = \frac{1}{t}\ln (\frac{x_o}{x}) \\ k = \frac{1}{43}\ln (\frac{x_o}{0.55_o})\\ k = 0.013903 min^-^1

<h3>Half Life </h3>

The half-life of a reaction is said to be the time required for the initial amount of the reactant to reach half it's original size.

x = \frac{x_o}{2} \\t = t_\frac{1}{2} \\t_\frac{1}{2} = \frac{1}{k}\ln(\frac{x_o}{x_o/2})\\

Substitute the values

t_\frac{1}{2} = \frac{1}{k}\ln(2)=\frac{0.6931}{0.013903}\\t_\frac{1}{2}= 49.85 min = 50 min

The half-life of the reaction is 50 minutes

Learn more on half-life of a first order reaction here;

brainly.com/question/14936355

4 0
2 years ago
What is the significance of wanting to know what the pH of a solution is?
balu736 [363]

pH is an important parameter for many reactions to take place in solution and in biological systems. It is related to the concentration of H⁺ ions through the following expression:

pH = 1/[H⁺] = -log [H⁺]

Wanting to know the pH of a solution is equivalent to knowing the amount of hydrogen ions present. But the pH scale is more convenient than the concentration scale because pH usually takes values between 0 and 14.

  • When pH < 7 the solution is acid.
  • When pH = 7 the solution is neutral (like pure water).
  • When pH > 7 the solution is basic.
4 0
3 years ago
Does anyone know how to do this?
Sloan [31]

Answer

find out the number of moles and use the molar ratio (numbers in front of formulas (in this case they are all 1) to determine how many moles of each product you are going to get theoretically

n=m/M is the equation to use to get moles here

30.8 gm/32.04 g/mol=0.9612 moles of the methanol and also of the formaldehyde so

0.9612 moles of the formaldehyde x molar mass (M) 30.73 g/mol= 29.54 gm which is the theoretical yield you already have the actual yield of 24.7 gm

then divide the actual by the theoretical to get the % yield which is 83.6%

Explanation:

4 0
3 years ago
................................................................................................................................
viktelen [127]

Answer:

HmmmmmmmmmmI think the answer is 69

3 0
3 years ago
Read 2 more answers
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