6. Procedures: Cause

6.1. Subordinate Conjunctions of Cause

Used to highlight hazards or prevent equipment damage.

The subordinate conjunctions of cause can be categorized based on whether they focus on the Reason (the “Why”; the existing threat) or Purpose (the “Goal”; the intended outcome).

6.2. Conjunctions of Reason (The “Why”)

These explain the existing cause, risk, or rationale behind a safety rule.

Conjunctions

  • As: Links a dangerous state to a required action.

  • As a result of: Describes an outcome that follows from a prior condition.

  • Because: Explains, for the first time, the specific chemical or physical mechanism that makes an instruction necessary.

  • For: (Formal) Provides the written justification for a safety rule typically following a firm imperative (“must”).

  • In case: Anticipates a hypothetical future risk and justifies a precautionary action.

  • Since: Provides the rationale for an established safety rule based on an already established, widely accepted property of the material, component, or system.

Examples

  1. Chemistry: Handle the glass rod carefully as it becomes extremely brittle after heating.

  2. Chemistry: Evacuate the fume cupboard and ventilate the room immediately as a result of any detected rise in hydrogen sulphide above 1 part per million (ppm).

  3. Chemistry: Add the acid dropwise because a rapid addition may cause the solution to splatter.

  4. Physics: Store the radioactive source in the lead-lined container at all times when not in active use, for prolonged exposure to unshielded gamma radiation poses a serious health hazard to laboratory personnel.

  5. Biology: Label all specimen jars before beginning dissection in case samples become mixed up during the procedure.

  6. Physics: Do not exceed 5 volts since the resistor is prone to overheating at higher currents.

Fill in the Gaps — Conjunctions of Reason

Fill in the gaps with the most appropriate conjunction:

Word list (A → Z): as • as a result of • because • for • in case • since

  1. Chemistry: Handle the glass rod with care __________ it becomes extremely brittle once it has been heated.

  2. Earth Science: Halt the drilling operation immediately __________ any observed increase in methane readings above the safe threshold, and do not resume until the site has been ventilated.

  3. Chemistry: Add the acid to the solution dropwise __________ a rapid addition will cause an exothermic surge that may shatter the beaker.

  4. Physics: The radioactive source must be returned to its lead-lined container after every use, __________ unshielded gamma radiation presents a cumulative and serious health hazard to all laboratory personnel.

  5. Biology: Label every specimen jar with the sample ID before beginning dissection __________ two or more samples are accidentally mixed during the procedure.

  6. Physics: Do not allow the supply voltage to exceed 5 volts, __________ this resistor has a well-documented tendency to overheat at higher currents.

Reveal Answer Key

1. as — the brittle state is a dangerous concurrent condition that makes careful handling necessary right now; because would suggest the brittleness is a new piece of information explaining a risk, whereas as links a present state to an immediate required action.

2. as a result of — the halt is a mandatory protocol triggered by a specific measurable outcome (methane exceeding a threshold); the “and do not resume until” tail confirms this is a procedural consequence, not a background explanation, ruling out because and since.

3. because — introduces the specific, technical chemical risk (exothermic surge) that explains the instruction; since would imply this is background knowledge the reader already holds, but the risk mechanism is being stated explicitly for the first time.

4. for — the formal register of the full sentence (“must be returned… after every use”) calls for for as a written justification; because or since would sound like spoken explanation rather than a documented safety protocol.

5. in case — the mixing is a hypothetical future risk, not a certainty; because would imply the mixing has already happened, and since would imply it always happens.

6. since — the overheating tendency is presented as an established, known property of this component (“well-documented”), making since the natural choice for a rationale that the reader is expected to already accept as fact.

6.3. As vs. Since vs. Because

Here are 3 targeted questions for each confusable pair, with the disambiguation built into the sentence itself:

Fill in the Gaps — As vs. Since

Fill in the gaps with the most appropriate conjunction:

Word list (A → Z): as • since

  1. Chemistry: Do not leave the sodium exposed to open air __________ it reacts spontaneously with atmospheric moisture — you can see the surface already beginning to discolour.

  2. Biology: Autoclave all glassware before use __________ non-sterile equipment is a well-established source of culture contamination in any microbiology laboratory.

Reveal Answer Key

  1. as — “you can see the surface already beginning to discolour” makes the hazard visibly present right now.

  2. since — “well-established source” signals accepted background knowledge.

Fill in the Gaps — Because vs. Since

Fill in the gaps with the most appropriate conjunction:

Word list (A → Z): because • since

  1. Physics: Do not touch the transformer casing during operation __________ the outer shell accumulates a residual static charge that is not discharged by simply switching the unit off.

  2. Chemistry: Store flammable solvents away from ignition sources __________ their vapours can ignite at room temperature.

Reveal Answer Key

  1. because — the residual static mechanism is specific and non-obvious; the reader cannot be expected to already know it.

  2. since — vapour flammability at room temperature is standard, assumed knowledge in any chemistry course.

Fill in the Gaps — As vs. Because

Fill in the gaps with the most appropriate conjunction:

Word list (A → Z): as • because

  1. Earth Science: Secure all core samples in padded cases immediately __________ the extraction process leaves the rock under internal stress that makes it prone to sudden fracture.

  2. Biology: Handle the petri dishes on a flat surface __________ the agar has not yet fully solidified and will shift if tilted.

Reveal Answer Key

  1. because — internal stress is a non-visible mechanism being explained for the first time.

  2. as — the not-yet-solidified state is directly observable at the moment of handling.

6.4. Conjunctions of Purpose (The Goal)

These stipulate the desired outcome or the negative event being avoided.

Each functional meaning has both a formal and an everyday register — choosing the right one depends on whether you are writing a formal laboratory protocol, or a general instruction.

Conjunctions

Everyday Register

Formal Register

Function

So that

In order that

Introduces a purpose clause with a finite verb (subject + verb follows).

So as to

In order to

Introduces a purpose clause with an infinitive (base verb follows).

Examples

Everyday register:

  1. Chemistry: Tighten the flask stopper firmly so that pressure does not build up and force the stopper free during heating.

  2. Biology: Tilt the microscope slide at a shallow angle so as to avoid trapping air bubbles beneath the cover slip.

Formal register:

  1. Chemistry: Keep the condenser running throughout the entire distillation in order that vapour is fully recovered and solvent loss is minimised.

  2. Physics: Position the blast shield directly in front of the capacitor bank in order to deflect any fragments in the event of a catastrophic discharge.

Match — Conjunctions of Purpose: Matching Clauses

Match each independent clause (A-D) with the correct dependent clause (1-4) by writing the appropriate number in the blank.

Independent Clauses

  1. Seal the reaction vessel immediately so that ____________

  2. Centrifuge the sample at low speed first in order that ____________

  3. Earth the apparatus before connecting the power supply in order to ____________

  4. Collect sediment samples from at least three separate locations so as to ____________

Dependent Clauses

  1. … prevent residual charge from causing an unexpected discharge.

  2. … no volatile vapours escape into the laboratory atmosphere.

  3. … ensure the data is representative of the wider geological formation.

  4. … the denser cellular material separates before the final high-speed spin is performed.

Reveal Answer Key
A → 2

Seal the reaction vessel immediately so that no volatile vapours escape into the laboratory atmosphere.

B → 4

Centrifuge the sample at low speed first in order that the denser cellular material separates before the final high-speed spin is performed.

C → 1

Earth the apparatus before connecting the power supply in order to prevent residual charge from causing an unexpected discharge.

D → 3

Collect sediment samples from at least three separate locations so as to ensure the data is representative of the wider geological formation.

Multiple Choice: Reason vs. Purpose

Identify whether the bolded conjunction introduces a Reason (explaining an existing risk/cause) or a Purpose (stating a goal to avoid a potential risk).

  1. Biology: Seal the petri dishes with Parafilm so that airborne fungal spores do not contaminate the culture.

  1. Reason

  1. Purpose

  1. Chemistry: Do not inhale the vapors directly since the compound is a known respiratory irritant.

  1. Reason

  1. Purpose

  1. Physics: Wear insulated gloves in order to prevent accidental electrical discharge while handling the Van de Graaff generator.

  1. Reason

  1. Purpose

  1. Earth Science: Wear safety goggles as the risk of flying rock fragments is high when using a rock hammer.

  1. Chemistry: Keep a neutralizing agent nearby in case a corrosive liquid is spilled during the titration.

Reveal Answer Key

  1. B Purpose — “So that” defines the goal of avoiding contamination.

  1. A Reason — “Since” explains the inherent dangerous quality of the compound.

  1. B Purpose — “In order to” states the specific goal of the safety action.

  1. A Reason — “As” identifies the underlying cause or existing risk factor.

  1. B Purpose — “In case” prepares for a specific potential event or goal.