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2 years ago

By replacing hardware safety features with software controls in the therac-25 machine, aecl was able to?

Chemistry

1 answer:

Ipatiy [6.2K]2 years ago

5 0

Therac-25, AECL was able to reduce costs by replacing hardware safety features with software controls.

the Therac-25 was a laptop-controlled radiation therapy machine produced by Atomic energy state Canada limited in 1982 after the Therac-6 and Therac-20 units. It was involved in at least six accidents between 1985 and 1987, in which patients were given massive overdoses state radiation.

The Therac-25 machine was a state-of-the-art linear accelerator developed by using the company Atomic strength Canada restricted (AECL) and a French company CGR to provide radiation treatment to cancer sufferers. The Therac-25 become the most computerized and complicated radiation therapy device state its time.

learn more about cancer here brainly.com/question/11710623

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What is the purpose of galvanization?

frutty [35]

Galvanizing protects from rust in a number of ways: It forms a barrier that prevents corrosive substances from reaching the underlying steel or iron. The zinc serves as a sacrificial anode so that even if the coating is scratched, the exposed steel will still be protected by the remaining zinc.

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3 years ago

A scientist observed a 5-mL sample of an unknown substance. It is a blue liquid with a density of 1.2 g/cm. the substance reacts

LenaWriter [7]

Characteristic properties can be used to describe and identify the substances, while non-characteristic properties, although can be used to describe the substances, cannot be used to identify them.

Temperature, mass, color, shape and volume are examples of non-characteristic properties.

Density, boiling point, melting point, chemical reactivity are examples of characteristic properties.

List of the properties observed by the scientist:
-----------------------------------------------------------------
Property                                     Type of property
----------------------------------------------------------------
Volume: 5 ml                              non-characteristic
----------------------------------------------------------------
Color: blue                                 non-characteristic
----------------------------------------------------------------
State: liquid                                characteristic
------------------------------------------------------------
density: 1.2 g/cm                        characteristic
------------------------------------------------------------
Reaction: reacts with CO2         characteristic
----------------------------------------------------------

5 0

3 years ago

12a. How does the model of the volcano provide evidence for the cycling of Earth materials through the rock cycle?

Bond [772]

Answer:

lava is coming from the crust

Explanation:

volcano's explode with lava because the crust pushes it out

6 0

2 years ago

Combustibilty defined?

Phantasy [73]

Capable of catching fire

8 0

3 years ago

Rank these acids according to their expected pKa values.

givi [52]

Answer:

According to their expected pKa values, the order of those acids should be:

1- Cl2CHCOOH is the strongest acid and the lowest pKa.

2- ClCH2COOH is a strong acid, but no more than the first. Medium pKa value.

3- ClCH2CH2COOH is a strong acid, but no more than the two previous acids. High pKa value.

4- CH3CH2COOH is the weakest acid, so the highest pKa value.

Explanation:

The pKa values are the negative logarithm of dissociation constant. It represents the relative strengths of the acids. Stronger acids show smaller pKa values and weak acids present larger pKa value. The stronger the acid, the weaker it's the conjugate base. The larger the pKa of the conjugate base, the stronger the acid. The strength of an acid is inversely related to the strength of its conjugate.

Conjugate bases are the substance that has one less proton than the parent acid. The conjugate base of the acid presented in the problem are:

ClCH2COOH -> ClCH2COO- + H+

ClCH2CH2COOH -> ClCH2CH2COO- + H+

CH3CH2COOH -> CH3CH2COO- + H+

Cl2CHCOOH -> Cl2CHCOO - + H+

Cl2CHCOOH. The negative charge presented on its conjugate base is by resonance and inductive effect. This is the strongest acid.

ClCH2COOH. A negative charge is stabilized by resonance and electron-withdrawing but only one atom is present. So this acid is less strong than the first one.

ClCH2CH2COOH. The negative charge is stabilized by resonance and electron-withdrawing atom but the effect is less compared to the two acids showed previously.

CH3CH2COOH. The negative charge is stabilized by resonance and destabilized due to CH3 group. This is the weakest acid among the problem.

Stronger acids have smaller pKa values and weak acids have larger pKa values. Due to the information present in this problem, Cl2CHCOOH is the strongest acid and the lowest pKa. CH3CH2COOH is the weakest acid, so the highest pKa value.

Finally, we can conclude that according to their expected pKa values, the order of those acids should be:

1- Cl2CHCOOH is the strongest acid and the lowest pKa.

2- ClCH2COOH is a strong acid, but no more than the first. Medium pKa value.

3- ClCH2CH2COOH is a strong acid, but no more than the two previous acids. High pKa value.

4- CH3CH2COOH is the weakest acid, so the highest pKa value.

3 0

3 years ago