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Crank
3 years ago
9

Which of the following is NOT a sign of a chemical reaction:

Chemistry
2 answers:
Sergeeva-Olga [200]3 years ago
7 0
The answer is B. Precipitation
Liono4ka [1.6K]3 years ago
3 0
I think it’s B. I apologize if I was incorrect.
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You are asked to go into the lab and prepare an acetic acid - sodium acetate buffer solution with a ph of 4.00  0.02. what mola
Oxana [17]
Hello!

To solve this problem we are going to use the Henderson-Hasselbach equation and clear for the molar ratio. Keep in mind that we need the value for Acetic Acid's pKa, which can be found in tables and is 4,76:

 pH=pKa + log ( \frac{[CH_3COONa]}{[CH_3COOH]} )

\frac{[CH_3COOH]}{[CH_3COONa}= 10^{(pH-pKa)^{-1}}=10^{(4-4,76)^{-1}}=5,75

So, the mole ratio of CH₃COOH to CH₃COONa is 5,75

Have a nice day!

5 0
3 years ago
4. Explain how radioactive isotopes are used to detect health problems.
drek231 [11]
Radioisotopes are widely used to diagnose disease and as effective treatment tools. For diagnosis, the isotope is administered and then located in the body using a scanner of some sort.
6 0
3 years ago
A mixture contains 20% iron ions by mass. What mass of iron chloride (FeCl) would
omeli [17]

Mass of iron chloride (FeCl₂) : 22.68 g

<h3>Further explanation</h3>

Proust stated the Comparative Law that compounds are formed from elements with the same Mass Comparison so that the compound has a fixed composition of elements

In the same compound, although from different sources and formed by different processes, it will still have the same composition/comparison

With this law, we can calculate how many grams an element is needed to make a compound with a certain mass, as desired

<h3 />

\tt mass~Fe=\dfrac{Ar~Fe}{MW~FeCl_2}\times mass~FeCl_2

The iron ions in 50 g mixture :

\tt 20\%\times 50~g=10~g

\tt 10=\dfrac{56}{127}\times mass~FeCl_2\\\\mass~FeCl_2=22.68~g

8 0
3 years ago
Write the mechanism for the acid catalyzed hydrolysis of methyl benzoate
Elis [28]
Hydrolysis of Methyl Benzoate yields Benzoic Acid and Methanol. This reaction is also called as Tranesterification (reverse of esterification). Acid in this reaction protonates the carbonyl oxygen, resulting in increasing electrophillic character of carbonyl carbon. Water acts as a nucleophile and methoxide leaves as a good leaving group. Mechanism is shown below,

7 0
3 years ago
Describe the trend (pattern) in the numbers of mobile phone owners in the Uk since 1990.
Inessa05 [86]

Explanation:

<em><u>SMARTPHONE OWNERSHIP IS GROWING RAPIDLY AROUND THE WORLD, BUT NOT ALWAYS THE SAME.</u></em>

In emerging economies, the use of technology is still more common among the young and the educated

A farmer takes a selfie with a smartphone at a rally in Jaipur, India. (Vishal Bhatnagar/AFP/Getty Images)

A farmer takes a selfie with a smartphone at a rally in Jaipur, India. (Vishal Bhatnagar/AFP/Getty Images)

The chart shows that smartphone ownership in advanced economies is higher than in emerging economies.

Mobile technology has spread rapidly around the world. Today, it is estimated that more than 5 billion people have mobile devices, and more than half of these connections are smartphones. But growth in mobile technology so far has been unequal, either nationwide or within it. People in advanced economies are more likely to have mobile phones - smartphones in particular - and more likely to use the internet and social media than people in emerging economies. For example, a median of 76% across the 18 advanced economies surveyed have a smartphone, compared to a median of only 45% in emerging economies.

Smartphone ownership can vary by country, and even across developed economies. While about nine in ten or more South Koreans, Israelis and the Netherlands own a smartphone, the ownership rate is closer to six in ten in other developed countries such as Poland, Russia and Greece. In emerging economies as well, smartphone ownership rates vary significantly, from a high of 60% in South Africa and Brazil to just around four in ten in Indonesia, Kenya and Nigeria. Among the countries surveyed, ownership was lowest in India, where only 24% reported having a smartphone.

4 0
2 years ago
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